diff --git a/libraries/rush-lib/src/api/ApprovedPackagesConfiguration.ts b/libraries/rush-lib/src/api/ApprovedPackagesConfiguration.ts
index 6bbb3b7b412..867370ada20 100644
--- a/libraries/rush-lib/src/api/ApprovedPackagesConfiguration.ts
+++ b/libraries/rush-lib/src/api/ApprovedPackagesConfiguration.ts
@@ -59,13 +59,13 @@ const _jsonSchema: JsonSchema = JsonSchema.fromLoadedObject(schemaJson);
 export class ApprovedPackagesConfiguration {
   public items: ApprovedPackagesItem[] = [];
 
-  private _itemsByName: Map<string, ApprovedPackagesItem> = new Map<string, ApprovedPackagesItem>();
+  #itemsByName: Map<string, ApprovedPackagesItem> = new Map<string, ApprovedPackagesItem>();
 
-  private _loadedJson!: IApprovedPackagesJson;
-  private _jsonFilename: string;
+  #loadedJson!: IApprovedPackagesJson;
+  #jsonFilename: string;
 
   public constructor(jsonFilename: string) {
-    this._jsonFilename = jsonFilename;
+    this.#jsonFilename = jsonFilename;
     this.clear();
   }
 
@@ -73,8 +73,8 @@ export class ApprovedPackagesConfiguration {
    * Clears all the settings, returning to an empty state.
    */
   public clear(): void {
-    this._itemsByName.clear();
-    this._loadedJson = {
+    this.#itemsByName.clear();
+    this.#loadedJson = {
       // Ensure this comes first in the key ordering
       $schema: '',
       packages: []
@@ -82,16 +82,16 @@ export class ApprovedPackagesConfiguration {
   }
 
   public getItemByName(packageName: string): ApprovedPackagesItem | undefined {
-    return this._itemsByName.get(packageName);
+    return this.#itemsByName.get(packageName);
   }
 
   public addOrUpdatePackage(packageName: string, reviewCategory: string): boolean {
     let changed: boolean = false;
 
-    let item: ApprovedPackagesItem | undefined = this._itemsByName.get(packageName);
+    let item: ApprovedPackagesItem | undefined = this.#itemsByName.get(packageName);
     if (!item) {
       item = new ApprovedPackagesItem(packageName);
-      this._addItem(item);
+      this.#addItem(item);
       changed = true;
     }
 
@@ -107,7 +107,7 @@ export class ApprovedPackagesConfiguration {
    * If the file exists, calls loadFromFile().
    */
   public tryLoadFromFile(approvedPackagesPolicyEnabled: boolean): boolean {
-    if (!FileSystem.exists(this._jsonFilename)) {
+    if (!FileSystem.exists(this.#jsonFilename)) {
       return false;
     }
 
@@ -116,7 +116,7 @@ export class ApprovedPackagesConfiguration {
     if (!approvedPackagesPolicyEnabled) {
       // eslint-disable-next-line no-console
       console.log(
-        `Warning: Ignoring "${path.basename(this._jsonFilename)}" because the` +
+        `Warning: Ignoring "${path.basename(this.#jsonFilename)}" because the` +
           ` "approvedPackagesPolicy" setting was not specified in ${RushConstants.rushJsonFilename}`
       );
     }
@@ -129,14 +129,14 @@ export class ApprovedPackagesConfiguration {
    */
   public loadFromFile(): void {
     const approvedPackagesJson: IApprovedPackagesJson = JsonFile.loadAndValidate(
-      this._jsonFilename,
+      this.#jsonFilename,
       _jsonSchema
     );
 
     this.clear();
 
     for (const browserPackage of approvedPackagesJson.packages) {
-      this._addItemJson(browserPackage, this._jsonFilename);
+      this.#addItemJson(browserPackage, this.#jsonFilename);
     }
   }
 
@@ -148,9 +148,9 @@ export class ApprovedPackagesConfiguration {
     // (which passed schema validation).
 
     // eslint-disable-next-line dot-notation
-    this._loadedJson['$schema'] = JsonSchemaUrls.approvedPackages;
+    this.#loadedJson['$schema'] = JsonSchemaUrls.approvedPackages;
 
-    this._loadedJson.packages = [];
+    this.#loadedJson.packages = [];
 
     this.items.sort((a: ApprovedPackagesItem, b: ApprovedPackagesItem) => {
       return a.packageName.localeCompare(b.packageName);
@@ -166,11 +166,11 @@ export class ApprovedPackagesConfiguration {
         allowedCategories: allowedCategories
       };
 
-      this._loadedJson.packages.push(itemJson);
+      this.#loadedJson.packages.push(itemJson);
     }
 
     // Save the file
-    let body: string = JsonFile.stringify(this._loadedJson);
+    let body: string = JsonFile.stringify(this.#loadedJson);
 
     // Unindent the allowedCategories array to improve readability
     body = body.replace(/("allowedCategories": +\[)([^\]]+)/g, (substring: string, ...args: string[]) => {
@@ -180,7 +180,7 @@ export class ApprovedPackagesConfiguration {
     // Add a header
     body = '// DO NOT ADD COMMENTS IN THIS FILE.  They will be lost when the Rush tool resaves it.\n' + body;
 
-    FileSystem.writeFile(this._jsonFilename, body, {
+    FileSystem.writeFile(this.#jsonFilename, body, {
       convertLineEndings: NewlineKind.CrLf
     });
   }
@@ -188,8 +188,8 @@ export class ApprovedPackagesConfiguration {
   /**
    * Helper function only used by the constructor when loading the file.
    */
-  private _addItemJson(itemJson: IApprovedPackagesItemJson, jsonFilename: string): void {
-    if (this._itemsByName.has(itemJson.name)) {
+  #addItemJson(itemJson: IApprovedPackagesItemJson, jsonFilename: string): void {
+    if (this.#itemsByName.has(itemJson.name)) {
       throw new Error(
         `Error loading package review file ${jsonFilename}:\n` +
           ` the name "${itemJson.name}" appears more than once`
@@ -202,18 +202,18 @@ export class ApprovedPackagesConfiguration {
         item.allowedCategories.add(allowedCategory);
       }
     }
-    this._addItem(item);
+    this.#addItem(item);
   }
 
   /**
    * Helper function that adds an already created ApprovedPackagesItem to the
    * list and set.
    */
-  private _addItem(item: ApprovedPackagesItem): void {
-    if (this._itemsByName.has(item.packageName)) {
+  #addItem(item: ApprovedPackagesItem): void {
+    if (this.#itemsByName.has(item.packageName)) {
       throw new InternalError('Duplicate key');
     }
     this.items.push(item);
-    this._itemsByName.set(item.packageName, item);
+    this.#itemsByName.set(item.packageName, item);
   }
 }
diff --git a/libraries/rush-lib/src/api/ChangeFile.ts b/libraries/rush-lib/src/api/ChangeFile.ts
index 1de74ec139a..3fe26f50f43 100644
--- a/libraries/rush-lib/src/api/ChangeFile.ts
+++ b/libraries/rush-lib/src/api/ChangeFile.ts
@@ -15,8 +15,8 @@ import { Git } from '../logic/Git';
  * This class represents a single change file.
  */
 export class ChangeFile {
-  private _changeFileData: IChangeFile;
-  private _rushConfiguration: RushConfiguration;
+  #changeFileData: IChangeFile;
+  #rushConfiguration: RushConfiguration;
 
   /**
    * @internal
@@ -30,8 +30,8 @@ export class ChangeFile {
       throw new Error(`rushConfiguration does not have a value`);
     }
 
-    this._changeFileData = changeFileData;
-    this._rushConfiguration = rushConfiguration;
+    this.#changeFileData = changeFileData;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   /**
@@ -39,7 +39,7 @@ export class ChangeFile {
    * @param data - change information
    */
   public addChange(data: IChangeInfo): void {
-    this._changeFileData.changes.push(data);
+    this.#changeFileData.changes.push(data);
   }
 
   /**
@@ -48,7 +48,7 @@ export class ChangeFile {
    */
   public getChanges(packageName: string): IChangeInfo[] {
     const changes: IChangeInfo[] = [];
-    for (const info of this._changeFileData.changes) {
+    for (const info of this.#changeFileData.changes) {
       if (info.packageName === packageName) {
         changes.push(info);
       }
@@ -63,7 +63,7 @@ export class ChangeFile {
    */
   public writeSync(): string {
     const filePath: string = this.generatePath();
-    JsonFile.save(this._changeFileData, filePath, {
+    JsonFile.save(this.#changeFileData, filePath, {
       ensureFolderExists: true
     });
     return filePath;
@@ -76,7 +76,7 @@ export class ChangeFile {
    */
   public generatePath(): string {
     let branch: string | undefined = undefined;
-    const git: Git = new Git(this._rushConfiguration);
+    const git: Git = new Git(this.#rushConfiguration);
     const repoInfo: gitInfo.GitRepoInfo | undefined = git.getGitInfo();
     branch = repoInfo && repoInfo.branch;
     if (!branch) {
@@ -89,13 +89,13 @@ export class ChangeFile {
     // flag rarely had any effect, and a second invocation would silently clobber the
     // change file written by the first one. See GitHub issue #2195.
     // example filename: yourbranchname_2017-05-01-20-20-30.json
-    const timestamp: string | undefined = this._getTimestamp(true);
+    const timestamp: string | undefined = this.#getTimestamp(true);
     const filename: string = branch
-      ? this._escapeFilename(`${branch}_${timestamp}.json`)
+      ? this.#escapeFilename(`${branch}_${timestamp}.json`)
       : `${timestamp}.json`;
     const filePath: string = path.join(
-      this._rushConfiguration.changesFolder,
-      ...this._changeFileData.packageName.split('/'),
+      this.#rushConfiguration.changesFolder,
+      ...this.#changeFileData.packageName.split('/'),
       filename
     );
     return filePath;
@@ -105,7 +105,7 @@ export class ChangeFile {
    * Gets the current time, formatted as YYYY-MM-DD-HH-MM
    * When useSeconds is true, the seconds are appended as well: YYYY-MM-DD-HH-MM-SS
    */
-  private _getTimestamp(useSeconds: boolean = false): string | undefined {
+  #getTimestamp(useSeconds: boolean = false): string | undefined {
     // Create a date string with the current time
 
     // dateString === "2016-10-19T22:47:49.606Z"
@@ -137,7 +137,7 @@ export class ChangeFile {
     return undefined;
   }
 
-  private _escapeFilename(filename: string, replacer: string = '-'): string {
+  #escapeFilename(filename: string, replacer: string = '-'): string {
     // Removes / ? < > \ : * | ", really anything that isn't a letter, number, '.' '_' or '-'
     const badCharacters: RegExp = /[^a-zA-Z0-9._-]/g;
     return filename.replace(badCharacters, replacer);
diff --git a/libraries/rush-lib/src/api/CobuildConfiguration.ts b/libraries/rush-lib/src/api/CobuildConfiguration.ts
index e397018ca44..b32caf977ee 100644
--- a/libraries/rush-lib/src/api/CobuildConfiguration.ts
+++ b/libraries/rush-lib/src/api/CobuildConfiguration.ts
@@ -76,9 +76,9 @@ export class CobuildConfiguration {
    */
   public readonly cobuildWithoutCacheAllowed: boolean;
 
-  private _cobuildLockProvider: ICobuildLockProvider | undefined;
-  private readonly _cobuildLockProviderFactory: CobuildLockProviderFactory;
-  private readonly _cobuildJson: ICobuildJson;
+  #cobuildLockProvider: ICobuildLockProvider | undefined;
+  readonly #cobuildLockProviderFactory: CobuildLockProviderFactory;
+  readonly #cobuildJson: ICobuildJson;
 
   private constructor(options: ICobuildConfigurationOptions) {
     const { cobuildJson, cobuildLockProviderFactory, rushConfiguration } = options;
@@ -91,8 +91,8 @@ export class CobuildConfiguration {
     this.cobuildWithoutCacheAllowed =
       rushConfiguration.experimentsConfiguration.configuration.allowCobuildWithoutCache ?? false;
 
-    this._cobuildLockProviderFactory = cobuildLockProviderFactory;
-    this._cobuildJson = cobuildJson;
+    this.#cobuildLockProviderFactory = cobuildLockProviderFactory;
+    this.#cobuildJson = cobuildJson;
   }
 
   /**
@@ -127,25 +127,25 @@ export class CobuildConfiguration {
   public async createLockProviderAsync(terminal: ITerminal): Promise<void> {
     if (this.cobuildFeatureEnabled) {
       terminal.writeLine(`Running cobuild (runner ${this.cobuildContextId}/${this.cobuildRunnerId})`);
-      const cobuildLockProvider: ICobuildLockProvider = await this._cobuildLockProviderFactory(
-        this._cobuildJson
+      const cobuildLockProvider: ICobuildLockProvider = await this.#cobuildLockProviderFactory(
+        this.#cobuildJson
       );
-      this._cobuildLockProvider = cobuildLockProvider;
-      await this._cobuildLockProvider.connectAsync();
+      this.#cobuildLockProvider = cobuildLockProvider;
+      await this.#cobuildLockProvider.connectAsync();
     }
   }
 
   public async destroyLockProviderAsync(): Promise<void> {
     if (this.cobuildFeatureEnabled) {
-      await this._cobuildLockProvider?.disconnectAsync();
+      await this.#cobuildLockProvider?.disconnectAsync();
     }
   }
 
   public getCobuildLockProvider(): ICobuildLockProvider {
-    if (!this._cobuildLockProvider) {
+    if (!this.#cobuildLockProvider) {
       throw new Error(`Cobuild lock provider has not been created`);
     }
-    return this._cobuildLockProvider;
+    return this.#cobuildLockProvider;
   }
 }
 
diff --git a/libraries/rush-lib/src/api/CommandLineConfiguration.ts b/libraries/rush-lib/src/api/CommandLineConfiguration.ts
index 53b5678f4ff..8ec4b5a3dee 100644
--- a/libraries/rush-lib/src/api/CommandLineConfiguration.ts
+++ b/libraries/rush-lib/src/api/CommandLineConfiguration.ts
@@ -233,7 +233,7 @@ export class CommandLineConfiguration {
   /**
    * A map of bulk command names to their corresponding synthetic phase identifiers
    */
-  private readonly _syntheticPhasesByTranslatedBulkCommandName: Map<string, IPhase> = new Map();
+  readonly #syntheticPhasesByTranslatedBulkCommandName: Map<string, IPhase> = new Map();
 
   /**
    * Use CommandLineConfiguration.loadFromFile()
@@ -332,7 +332,7 @@ export class CommandLineConfiguration {
       const safePhases: Set<IPhase> = new Set();
       const cycleDetector: Set<IPhase> = new Set();
       for (const phase of this.phases.values()) {
-        this._checkForPhaseSelfCycles(phase, cycleDetector, safePhases);
+        this.#checkForPhaseSelfCycles(phase, cycleDetector, safePhases);
       }
     }
 
@@ -445,7 +445,7 @@ export class CommandLineConfiguration {
 
           case RushConstants.bulkCommandKind: {
             // Translate the bulk command into a phased command
-            normalizedCommand = this._translateBulkCommandToPhasedCommand(command);
+            normalizedCommand = this.#translateBulkCommandToPhasedCommand(command);
             break;
           }
         }
@@ -480,7 +480,7 @@ export class CommandLineConfiguration {
       let buildCommand: Command | undefined = this.commands.get(RushConstants.buildCommandName);
       if (!buildCommand) {
         // If the build command was not specified in the config file, add the default build command
-        buildCommand = this._translateBulkCommandToPhasedCommand(DEFAULT_BUILD_COMMAND_JSON);
+        buildCommand = this.#translateBulkCommandToPhasedCommand(DEFAULT_BUILD_COMMAND_JSON);
         buildCommand.disableBuildCache = DEFAULT_BUILD_COMMAND_JSON.disableBuildCache;
         buildCommandPhases = buildCommand.phases;
         buildCommandOriginalPhases = buildCommand.originalPhases;
@@ -545,7 +545,7 @@ export class CommandLineConfiguration {
         if (normalizedParameter.associatedCommands) {
           for (const associatedCommandName of normalizedParameter.associatedCommands) {
             const syntheticPhase: IPhase | undefined =
-              this._syntheticPhasesByTranslatedBulkCommandName.get(associatedCommandName);
+              this.#syntheticPhasesByTranslatedBulkCommandName.get(associatedCommandName);
             if (syntheticPhase) {
               // If this parameter was associated with a bulk command, include the association
               // with the synthetic phase
@@ -598,7 +598,7 @@ export class CommandLineConfiguration {
    * @param phasesInPath The current path from the start node to `phase`
    * @param cycleFreePhases Phases that have already been fully walked and confirmed to not be in any cycles
    */
-  private _checkForPhaseSelfCycles(
+  #checkForPhaseSelfCycles(
     phase: IPhase,
     phasesInPath: Set<IPhase>,
     cycleFreePhases: Set<IPhase>
@@ -619,7 +619,7 @@ export class CommandLineConfiguration {
         );
       } else {
         phasesInPath.add(dependency);
-        this._checkForPhaseSelfCycles(dependency, phasesInPath, cycleFreePhases);
+        this.#checkForPhaseSelfCycles(dependency, phasesInPath, cycleFreePhases);
         phasesInPath.delete(dependency);
       }
     }
@@ -709,7 +709,7 @@ export class CommandLineConfiguration {
     (this.additionalPathFolders as string[]).unshift(pathFolder);
   }
 
-  private _translateBulkCommandToPhasedCommand(command: IBulkCommandJson): IPhasedCommandConfig {
+  #translateBulkCommandToPhasedCommand(command: IBulkCommandJson): IPhasedCommandConfig {
     const phaseName: string = command.name;
     const phase: IPhase = {
       name: phaseName,
@@ -730,7 +730,7 @@ export class CommandLineConfiguration {
     }
 
     this.phases.set(phaseName, phase);
-    this._syntheticPhasesByTranslatedBulkCommandName.set(command.name, phase);
+    this.#syntheticPhasesByTranslatedBulkCommandName.set(command.name, phase);
 
     const phases: Set<IPhase> = new Set([phase]);
 
diff --git a/libraries/rush-lib/src/api/CommonVersionsConfiguration.ts b/libraries/rush-lib/src/api/CommonVersionsConfiguration.ts
index 42b74f7e961..3b023bb3ded 100644
--- a/libraries/rush-lib/src/api/CommonVersionsConfiguration.ts
+++ b/libraries/rush-lib/src/api/CommonVersionsConfiguration.ts
@@ -65,10 +65,10 @@ const _jsonSchema: JsonSchema = JsonSchema.fromLoadedObject(schemaJson);
  * @public
  */
 export class CommonVersionsConfiguration {
-  private _preferredVersions: ProtectableMap<string, string>;
-  private _allowedAlternativeVersions: ProtectableMap<string, string[]>;
-  private _modified: boolean = false;
-  private _commonVersionsJsonHasEnsureConsistentVersionsProperty: boolean;
+  #preferredVersions: ProtectableMap<string, string>;
+  #allowedAlternativeVersions: ProtectableMap<string, string[]>;
+  #modified: boolean = false;
+  #commonVersionsJsonHasEnsureConsistentVersionsProperty: boolean;
 
   /**
    * Get the absolute file path of the common-versions.json file.
@@ -126,10 +126,10 @@ export class CommonVersionsConfiguration {
     filePath: string,
     rushConfiguration: RushConfiguration | undefined
   ) {
-    this._preferredVersions = new ProtectableMap<string, string>({
-      onSet: this._onSetPreferredVersions.bind(this)
+    this.#preferredVersions = new ProtectableMap<string, string>({
+      onSet: this.#onSetPreferredVersions.bind(this)
     });
-    this.preferredVersions = this._preferredVersions.protectedView;
+    this.preferredVersions = this.#preferredVersions.protectedView;
 
     if (commonVersionsJson && commonVersionsJson.implicitlyPreferredVersions !== undefined) {
       this.implicitlyPreferredVersions = commonVersionsJson.implicitlyPreferredVersions;
@@ -137,10 +137,10 @@ export class CommonVersionsConfiguration {
       this.implicitlyPreferredVersions = undefined;
     }
 
-    this._allowedAlternativeVersions = new ProtectableMap<string, string[]>({
-      onSet: this._onSetAllowedAlternativeVersions.bind(this)
+    this.#allowedAlternativeVersions = new ProtectableMap<string, string[]>({
+      onSet: this.#onSetAllowedAlternativeVersions.bind(this)
     });
-    this.allowedAlternativeVersions = this._allowedAlternativeVersions.protectedView;
+    this.allowedAlternativeVersions = this.#allowedAlternativeVersions.protectedView;
 
     const subspacesFeatureEnabled: boolean | undefined = rushConfiguration?.subspacesFeatureEnabled;
     const rushJsonEnsureConsistentVersions: boolean | undefined =
@@ -165,7 +165,7 @@ export class CommonVersionsConfiguration {
 
     this.ensureConsistentVersions =
       commonVersionsEnsureConsistentVersions ?? rushJsonEnsureConsistentVersions ?? false;
-    this._commonVersionsJsonHasEnsureConsistentVersionsProperty =
+    this.#commonVersionsJsonHasEnsureConsistentVersionsProperty =
       commonVersionsEnsureConsistentVersions !== undefined;
 
     if (commonVersionsJson) {
@@ -224,7 +224,7 @@ export class CommonVersionsConfiguration {
   public getPreferredVersionsHash(): string {
     // Sort so that the hash is stable
     const orderedPreferredVersions: Map<string, string> = new Map<string, string>(
-      this._preferredVersions.protectedView
+      this.#preferredVersions.protectedView
     );
     Sort.sortMapKeys(orderedPreferredVersions);
 
@@ -238,12 +238,12 @@ export class CommonVersionsConfiguration {
    * @deprecated Use {@link CommonVersionsConfiguration.saveAsync} method instead.
    */
   public save(): boolean {
-    if (this._modified) {
-      JsonFile.save(this._serialize(), this.filePath, {
+    if (this.#modified) {
+      JsonFile.save(this.#serialize(), this.filePath, {
         updateExistingFile: true,
         ignoreUndefinedValues: true
       });
-      this._modified = false;
+      this.#modified = false;
       return true;
     }
 
@@ -254,12 +254,12 @@ export class CommonVersionsConfiguration {
    * Writes the "common-versions.json" file to disk, using the filename that was passed to loadFromFile().
    */
   public async saveAsync(): Promise<boolean> {
-    if (this._modified) {
-      await JsonFile.saveAsync(this._serialize(), this.filePath, {
+    if (this.#modified) {
+      await JsonFile.saveAsync(this.#serialize(), this.filePath, {
         updateExistingFile: true,
         ignoreUndefinedValues: true
       });
-      this._modified = false;
+      this.#modified = false;
       return true;
     }
 
@@ -275,38 +275,38 @@ export class CommonVersionsConfiguration {
     return allPreferredVersions;
   }
 
-  private _onSetPreferredVersions(
+  #onSetPreferredVersions(
     source: ProtectableMap<string, string>,
     key: string,
     value: string
   ): string {
     PackageNameParsers.permissive.validate(key);
 
-    this._modified = true;
+    this.#modified = true;
 
     return value;
   }
 
-  private _onSetAllowedAlternativeVersions(
+  #onSetAllowedAlternativeVersions(
     source: ProtectableMap<string, string[]>,
     key: string,
     value: string[]
   ): string[] {
     PackageNameParsers.permissive.validate(key);
 
-    this._modified = true;
+    this.#modified = true;
 
     return value;
   }
 
-  private _serialize(): ICommonVersionsJson {
+  #serialize(): ICommonVersionsJson {
     let preferredVersions: ICommonVersionsJsonVersionMap | undefined;
-    if (this._preferredVersions.size) {
+    if (this.#preferredVersions.size) {
       preferredVersions = _serializeTable(this.preferredVersions);
     }
 
     let allowedAlternativeVersions: ICommonVersionsJsonVersionsMap | undefined;
-    if (this._allowedAlternativeVersions.size) {
+    if (this.#allowedAlternativeVersions.size) {
       allowedAlternativeVersions = _serializeTable(
         this.allowedAlternativeVersions
       ) as ICommonVersionsJsonVersionsMap;
@@ -317,7 +317,7 @@ export class CommonVersionsConfiguration {
       preferredVersions,
       implicitlyPreferredVersions: this.implicitlyPreferredVersions,
       allowedAlternativeVersions,
-      ensureConsistentVersions: this._commonVersionsJsonHasEnsureConsistentVersionsProperty
+      ensureConsistentVersions: this.#commonVersionsJsonHasEnsureConsistentVersionsProperty
         ? this.ensureConsistentVersions
         : undefined
     };
diff --git a/libraries/rush-lib/src/api/CustomTipsConfiguration.ts b/libraries/rush-lib/src/api/CustomTipsConfiguration.ts
index 8bc12a439e8..b416496f1a8 100644
--- a/libraries/rush-lib/src/api/CustomTipsConfiguration.ts
+++ b/libraries/rush-lib/src/api/CustomTipsConfiguration.ts
@@ -311,7 +311,7 @@ export class CustomTipsConfiguration {
     const severityOfOriginalMessage: CustomTipSeverity =
       CustomTipsConfiguration.customTipRegistry[tipId].severity;
 
-    this._writeMessageWithPipes(terminal, severityOfOriginalMessage, tipId);
+    this.#writeMessageWithPipes(terminal, severityOfOriginalMessage, tipId);
   }
 
   /**
@@ -322,7 +322,7 @@ export class CustomTipsConfiguration {
    * @internal
    */
   public _showInfoTip(terminal: ITerminal, tipId: CustomTipId): void {
-    this._writeMessageWithPipes(terminal, CustomTipSeverity.Info, tipId);
+    this.#writeMessageWithPipes(terminal, CustomTipSeverity.Info, tipId);
   }
 
   /**
@@ -333,7 +333,7 @@ export class CustomTipsConfiguration {
    * @internal
    */
   public _showWarningTip(terminal: ITerminal, tipId: CustomTipId): void {
-    this._writeMessageWithPipes(terminal, CustomTipSeverity.Warning, tipId);
+    this.#writeMessageWithPipes(terminal, CustomTipSeverity.Warning, tipId);
   }
 
   /**
@@ -344,10 +344,10 @@ export class CustomTipsConfiguration {
    * @internal
    */
   public _showErrorTip(terminal: ITerminal, tipId: CustomTipId): void {
-    this._writeMessageWithPipes(terminal, CustomTipSeverity.Error, tipId);
+    this.#writeMessageWithPipes(terminal, CustomTipSeverity.Error, tipId);
   }
 
-  private _writeMessageWithPipes(terminal: ITerminal, severity: CustomTipSeverity, tipId: CustomTipId): void {
+  #writeMessageWithPipes(terminal: ITerminal, severity: CustomTipSeverity, tipId: CustomTipId): void {
     const customTipJsonItem: ICustomTipItemJson | undefined = this.providedCustomTipsByTipId.get(tipId);
     if (customTipJsonItem) {
       let writeFunction:
diff --git a/libraries/rush-lib/src/api/EventHooks.ts b/libraries/rush-lib/src/api/EventHooks.ts
index d53fdd365ad..26395ca73a5 100644
--- a/libraries/rush-lib/src/api/EventHooks.ts
+++ b/libraries/rush-lib/src/api/EventHooks.ts
@@ -43,17 +43,17 @@ export enum Event {
  * @beta
  */
 export class EventHooks {
-  private _hooks: Map<Event, string[]>;
+  #hooks: Map<Event, string[]>;
 
   /**
    * @internal
    */
   public constructor(eventHooksJson: IEventHooksJson) {
-    this._hooks = new Map<Event, string[]>();
+    this.#hooks = new Map<Event, string[]>();
     for (const [name, eventHooks] of Object.entries(eventHooksJson)) {
       const eventName: Event | undefined = Enum.tryGetValueByKey(Event, name);
       if (eventName) {
-        this._hooks.set(eventName, [...eventHooks]);
+        this.#hooks.set(eventName, [...eventHooks]);
       }
     }
   }
@@ -63,6 +63,6 @@ export class EventHooks {
    * @param event - Rush event
    */
   public get(event: Event): string[] {
-    return this._hooks.get(event) || [];
+    return this.#hooks.get(event) || [];
   }
 }
diff --git a/libraries/rush-lib/src/api/LastInstallFlag.ts b/libraries/rush-lib/src/api/LastInstallFlag.ts
index a0af3df9dd8..61e29ccc040 100644
--- a/libraries/rush-lib/src/api/LastInstallFlag.ts
+++ b/libraries/rush-lib/src/api/LastInstallFlag.ts
@@ -90,7 +90,7 @@ export class LastInstallFlag extends FlagFile<Partial<ILastInstallFlagJson>> {
    * Returns true if the file exists and the contents match the current state.
    */
   public override async isValidAsync(): Promise<boolean> {
-    return await this._isValidAsync(false, {});
+    return await this.#isValidAsync(false, {});
   }
 
   /**
@@ -102,10 +102,10 @@ export class LastInstallFlag extends FlagFile<Partial<ILastInstallFlagJson>> {
   public async checkValidAndReportStoreIssuesAsync(
     options: ILockfileValidityCheckOptions & { rushVerb: string }
   ): Promise<boolean> {
-    return this._isValidAsync(true, options);
+    return this.#isValidAsync(true, options);
   }
 
-  private async _isValidAsync(
+  async #isValidAsync(
     checkValidAndReportStoreIssues: boolean,
     { rushVerb = 'update', statePropertiesToIgnore }: ILockfileValidityCheckOptions = {}
   ): Promise<boolean> {
diff --git a/libraries/rush-lib/src/api/PackageJsonEditor.ts b/libraries/rush-lib/src/api/PackageJsonEditor.ts
index c9baeb73e0f..a19c06658ff 100644
--- a/libraries/rush-lib/src/api/PackageJsonEditor.ts
+++ b/libraries/rush-lib/src/api/PackageJsonEditor.ts
@@ -22,29 +22,29 @@ export enum DependencyType {
  * @public
  */
 export class PackageJsonDependency {
-  private _version: string;
-  private _onChange: () => void;
+  #version: string;
+  #onChange: () => void;
 
   public readonly name: string;
   public readonly dependencyType: DependencyType;
 
   public constructor(name: string, version: string, type: DependencyType, onChange: () => void) {
     this.name = name;
-    this._version = version;
+    this.#version = version;
     this.dependencyType = type;
-    this._onChange = onChange;
+    this.#onChange = onChange;
   }
 
   public get version(): string {
-    return this._version;
+    return this.#version;
   }
 
   public setVersion(newVersion: string): void {
     if (!semver.valid(newVersion) && !semver.validRange(newVersion)) {
       throw new Error(`Cannot set version to invalid value: "${newVersion}"`);
     }
-    this._version = newVersion;
-    this._onChange();
+    this.#version = newVersion;
+    this.#onChange();
   }
 }
 
@@ -52,19 +52,19 @@ export class PackageJsonDependency {
  * @public
  */
 export class PackageJsonDependencyMeta {
-  private _injected: boolean;
-  private _onChange: () => void;
+  #injected: boolean;
+  #onChange: () => void;
 
   public readonly name: string;
 
   public constructor(name: string, injected: boolean, onChange: () => void) {
     this.name = name;
-    this._injected = injected;
-    this._onChange = onChange;
+    this.#injected = injected;
+    this.#onChange = onChange;
   }
 
   public get injected(): boolean {
-    return this._injected;
+    return this.#injected;
   }
 }
 
@@ -72,20 +72,20 @@ export class PackageJsonDependencyMeta {
  * @public
  */
 export class PackageJsonEditor {
-  private readonly _dependencies: Map<string, PackageJsonDependency>;
+  readonly #dependencies: Map<string, PackageJsonDependency>;
   // NOTE: The "devDependencies" section is tracked separately because sometimes people
   // will specify a specific version for development, while *also* specifying a broader
   // SemVer range in one of the other fields for consumers.  Thus "dependencies", "optionalDependencies",
   // and "peerDependencies" are mutually exclusive, but "devDependencies" is not.
-  private readonly _devDependencies: Map<string, PackageJsonDependency>;
+  readonly #devDependencies: Map<string, PackageJsonDependency>;
 
-  private readonly _dependenciesMeta: Map<string, PackageJsonDependencyMeta>;
+  readonly #dependenciesMeta: Map<string, PackageJsonDependencyMeta>;
 
   // NOTE: The "resolutions" field is a yarn specific feature that controls package
   // resolution override within yarn.
-  private readonly _resolutions: Map<string, PackageJsonDependency>;
-  private _modified: boolean;
-  private _sourceData: IPackageJson;
+  readonly #resolutions: Map<string, PackageJsonDependency>;
+  #modified: boolean;
+  #sourceData: IPackageJson;
 
   public readonly filePath: string;
 
@@ -94,8 +94,8 @@ export class PackageJsonEditor {
    */
   protected constructor(filepath: string, data: IPackageJson) {
     this.filePath = filepath;
-    this._sourceData = data;
-    this._modified = false;
+    this.#sourceData = data;
+    this.#modified = false;
 
     const {
       dependencies = {},
@@ -106,7 +106,7 @@ export class PackageJsonEditor {
       dependenciesMeta = {}
     } = data;
 
-    const _onChange: () => void = this._onChange.bind(this);
+    const _onChange: () => void = this.#onChange.bind(this);
 
     const optionalDependenciesSet: Set<string> = new Set(Object.keys(optionalDependencies));
     const peerDependenciesSet: Set<string> = new Set(Object.keys(peerDependencies));
@@ -154,27 +154,27 @@ export class PackageJsonEditor {
         new PackageJsonDependency(packageName, version, DependencyType.Peer, _onChange)
       ]);
 
-      this._dependencies = new Map([
+      this.#dependencies = new Map([
         ...dependenciesMapEntries,
         ...optionalDependenciesMapEntries,
         ...peerDependenciesMapEntries
       ]);
 
-      this._devDependencies = new Map(
+      this.#devDependencies = new Map(
         Object.entries(devDependencies).map(([packageName, version]) => [
           packageName,
           new PackageJsonDependency(packageName, version, DependencyType.Dev, _onChange)
         ])
       );
 
-      this._resolutions = new Map(
+      this.#resolutions = new Map(
         Object.entries(resolutions).map(([packageName, version]) => [
           packageName,
           new PackageJsonDependency(packageName, version, DependencyType.YarnResolutions, _onChange)
         ])
       );
 
-      this._dependenciesMeta = new Map(
+      this.#dependenciesMeta = new Map(
         Object.entries(dependenciesMeta).map(([packageName, { injected = false }]) => [
           packageName,
           new PackageJsonDependencyMeta(packageName, injected, _onChange)
@@ -182,8 +182,8 @@ export class PackageJsonEditor {
       );
 
       // (Do not sort this._resolutions because order may be significant; the RFC is unclear about that.)
-      Sort.sortMapKeys(this._dependencies);
-      Sort.sortMapKeys(this._devDependencies);
+      Sort.sortMapKeys(this.#dependencies);
+      Sort.sortMapKeys(this.#devDependencies);
     } catch (e) {
       throw new Error(`Error loading "${filepath}": ${(e as Error).message}`);
     }
@@ -207,32 +207,32 @@ export class PackageJsonEditor {
   }
 
   public get name(): string {
-    return this._sourceData.name;
+    return this.#sourceData.name;
   }
 
   public get version(): string {
-    return this._sourceData.version;
+    return this.#sourceData.version;
   }
 
   /**
    * The list of dependencies of type DependencyType.Regular, DependencyType.Optional, or DependencyType.Peer.
    */
   public get dependencyList(): ReadonlyArray<PackageJsonDependency> {
-    return [...this._dependencies.values()];
+    return [...this.#dependencies.values()];
   }
 
   /**
    * The list of dependencies of type DependencyType.Dev.
    */
   public get devDependencyList(): ReadonlyArray<PackageJsonDependency> {
-    return [...this._devDependencies.values()];
+    return [...this.#devDependencies.values()];
   }
 
   /**
    * The list of dependenciesMeta in package.json.
    */
   public get dependencyMetaList(): ReadonlyArray<PackageJsonDependencyMeta> {
-    return [...this._dependenciesMeta.values()];
+    return [...this.#dependenciesMeta.values()];
   }
 
   /**
@@ -243,15 +243,15 @@ export class PackageJsonEditor {
    * | 0000-selective-versions-resolutions.md RFC} for details.
    */
   public get resolutionsList(): ReadonlyArray<PackageJsonDependency> {
-    return [...this._resolutions.values()];
+    return [...this.#resolutions.values()];
   }
 
   public tryGetDependency(packageName: string): PackageJsonDependency | undefined {
-    return this._dependencies.get(packageName);
+    return this.#dependencies.get(packageName);
   }
 
   public tryGetDevDependency(packageName: string): PackageJsonDependency | undefined {
-    return this._devDependencies.get(packageName);
+    return this.#devDependencies.get(packageName);
   }
 
   public addOrUpdateDependency(
@@ -263,7 +263,7 @@ export class PackageJsonEditor {
       packageName,
       newVersion,
       dependencyType,
-      this._onChange.bind(this)
+      this.#onChange.bind(this)
     );
 
     // Rush collapses everything that isn't a devDependency into the dependencies
@@ -272,17 +272,17 @@ export class PackageJsonEditor {
       case DependencyType.Regular:
       case DependencyType.Optional:
       case DependencyType.Peer: {
-        this._dependencies.set(packageName, dependency);
+        this.#dependencies.set(packageName, dependency);
         break;
       }
 
       case DependencyType.Dev: {
-        this._devDependencies.set(packageName, dependency);
+        this.#devDependencies.set(packageName, dependency);
         break;
       }
 
       case DependencyType.YarnResolutions: {
-        this._resolutions.set(packageName, dependency);
+        this.#resolutions.set(packageName, dependency);
         break;
       }
 
@@ -291,7 +291,7 @@ export class PackageJsonEditor {
       }
     }
 
-    this._modified = true;
+    this.#modified = true;
   }
 
   public removeDependency(packageName: string, dependencyType: DependencyType): void {
@@ -299,17 +299,17 @@ export class PackageJsonEditor {
       case DependencyType.Regular:
       case DependencyType.Optional:
       case DependencyType.Peer: {
-        this._dependencies.delete(packageName);
+        this.#dependencies.delete(packageName);
         break;
       }
 
       case DependencyType.Dev: {
-        this._devDependencies.delete(packageName);
+        this.#devDependencies.delete(packageName);
         break;
       }
 
       case DependencyType.YarnResolutions: {
-        this._resolutions.delete(packageName);
+        this.#resolutions.delete(packageName);
         break;
       }
 
@@ -318,17 +318,17 @@ export class PackageJsonEditor {
       }
     }
 
-    this._modified = true;
+    this.#modified = true;
   }
 
   /**
    * @deprecated Use {@link PackageJsonEditor.saveIfModifiedAsync} method instead.
    */
   public saveIfModified(): boolean {
-    if (this._modified) {
-      this._modified = false;
-      this._sourceData = this._normalize(this._sourceData);
-      JsonFile.save(this._sourceData, this.filePath, {
+    if (this.#modified) {
+      this.#modified = false;
+      this.#sourceData = this.#normalize(this.#sourceData);
+      JsonFile.save(this.#sourceData, this.filePath, {
         updateExistingFile: true,
         jsonSyntax: JsonSyntax.Strict
       });
@@ -339,10 +339,10 @@ export class PackageJsonEditor {
   }
 
   public async saveIfModifiedAsync(): Promise<boolean> {
-    if (this._modified) {
-      this._modified = false;
-      this._sourceData = this._normalize(this._sourceData);
-      await JsonFile.saveAsync(this._sourceData, this.filePath, {
+    if (this.#modified) {
+      this.#modified = false;
+      this.#sourceData = this.#normalize(this.#sourceData);
+      await JsonFile.saveAsync(this.#sourceData, this.filePath, {
         updateExistingFile: true,
         jsonSyntax: JsonSyntax.Strict
       });
@@ -360,13 +360,13 @@ export class PackageJsonEditor {
    */
   public saveToObject(): IPackageJson {
     // Only normalize if we need to
-    const sourceData: IPackageJson = this._modified ? this._normalize(this._sourceData) : this._sourceData;
+    const sourceData: IPackageJson = this.#modified ? this.#normalize(this.#sourceData) : this.#sourceData;
     // Provide a clone to avoid reference back to the original data object
     return cloneDeep(sourceData);
   }
 
-  private _onChange(): void {
-    this._modified = true;
+  #onChange(): void {
+    this.#modified = true;
   }
 
   /**
@@ -375,7 +375,7 @@ export class PackageJsonEditor {
    * it will still need to be deep-cloned to avoid propogating changes back to the
    * original dataset.
    */
-  private _normalize(source: IPackageJson): IPackageJson {
+  #normalize(source: IPackageJson): IPackageJson {
     const normalizedData: IPackageJson = { ...source };
     delete normalizedData.dependencies;
     delete normalizedData.optionalDependencies;
@@ -383,10 +383,10 @@ export class PackageJsonEditor {
     delete normalizedData.devDependencies;
     delete normalizedData.resolutions;
 
-    const keys: string[] = [...this._dependencies.keys()].sort();
+    const keys: string[] = [...this.#dependencies.keys()].sort();
 
     for (const packageName of keys) {
-      const { dependencyType, name, version }: PackageJsonDependency = this._dependencies.get(packageName)!;
+      const { dependencyType, name, version }: PackageJsonDependency = this.#dependencies.get(packageName)!;
 
       switch (dependencyType) {
         case DependencyType.Regular: {
@@ -424,9 +424,9 @@ export class PackageJsonEditor {
       }
     }
 
-    const devDependenciesKeys: string[] = [...this._devDependencies.keys()].sort();
+    const devDependenciesKeys: string[] = [...this.#devDependencies.keys()].sort();
     for (const packageName of devDependenciesKeys) {
-      const { name, version }: PackageJsonDependency = this._devDependencies.get(packageName)!;
+      const { name, version }: PackageJsonDependency = this.#devDependencies.get(packageName)!;
 
       if (!normalizedData.devDependencies) {
         normalizedData.devDependencies = {};
@@ -436,8 +436,8 @@ export class PackageJsonEditor {
     }
 
     // (Do not sort this._resolutions because order may be significant; the RFC is unclear about that.)
-    for (const packageName of this._resolutions.keys()) {
-      const { name, version }: PackageJsonDependency = this._resolutions.get(packageName)!;
+    for (const packageName of this.#resolutions.keys()) {
+      const { name, version }: PackageJsonDependency = this.#resolutions.get(packageName)!;
 
       if (!normalizedData.resolutions) {
         normalizedData.resolutions = {};
diff --git a/libraries/rush-lib/src/api/RushConfiguration.ts b/libraries/rush-lib/src/api/RushConfiguration.ts
index 527ec92be93..86ae18f6778 100644
--- a/libraries/rush-lib/src/api/RushConfiguration.ts
+++ b/libraries/rush-lib/src/api/RushConfiguration.ts
@@ -227,7 +227,7 @@ const _jsonSchema: JsonSchema = JsonSchema.fromLoadedObject(schemaJson);
  * @public
  */
 export class RushConfiguration {
-  private readonly _pathTrees: Map<string, LookupByPath<RushConfigurationProject>>;
+  readonly #pathTrees: Map<string, LookupByPath<RushConfigurationProject>>;
 
   /**
    * @internal
@@ -235,17 +235,17 @@ export class RushConfiguration {
   public _currentVariantJsonLoadingPromise: Promise<ICurrentVariantJson | undefined> | undefined;
 
   // Lazily loaded when the projects() getter is called.
-  private _projects: RushConfigurationProject[] | undefined;
+  #projects: RushConfigurationProject[] | undefined;
 
   // Lazily loaded when the projectsByName() getter is called.
-  private _projectsByName: Map<string, RushConfigurationProject> | undefined;
+  #projectsByName: Map<string, RushConfigurationProject> | undefined;
 
   // Lazily loaded when the projectsByTag() getter is called.
-  private _projectsByTag: ReadonlyMap<string, ReadonlySet<RushConfigurationProject>> | undefined;
+  #projectsByTag: ReadonlyMap<string, ReadonlySet<RushConfigurationProject>> | undefined;
 
   // subspaceName -> subspace
-  private readonly _subspacesByName: Map<string, Subspace>;
-  private readonly _subspaces: Subspace[] = [];
+  readonly #subspacesByName: Map<string, Subspace>;
+  readonly #subspaces: Subspace[] = [];
 
   /**
    * The name of the package manager being used to install dependencies
@@ -663,7 +663,7 @@ export class RushConfiguration {
     this.subspacesConfiguration = SubspacesConfiguration.tryLoadFromDefaultLocation(this);
     this.subspacesFeatureEnabled = !!this.subspacesConfiguration?.subspacesEnabled;
 
-    this._subspacesByName = new Map();
+    this.#subspacesByName = new Map();
 
     const experimentsConfigFile: string = path.join(
       this.commonRushConfigFolder,
@@ -880,14 +880,14 @@ export class RushConfiguration {
 
     this.variants = variants;
 
-    this._pathTrees = new Map();
+    this.#pathTrees = new Map();
   }
 
-  private _initializeAndValidateLocalProjects(): void {
-    this._projects = [];
-    this._projectsByName = new Map<string, RushConfigurationProject>();
-    this._subspacesByName.clear();
-    this._subspaces.length = 0;
+  #initializeAndValidateLocalProjects(): void {
+    this.#projects = [];
+    this.#projectsByName = new Map<string, RushConfigurationProject>();
+    this.#subspacesByName.clear();
+    this.#subspaces.length = 0;
 
     // Build the subspaces map
     const subspaceNames: string[] = [];
@@ -910,10 +910,10 @@ export class RushConfiguration {
         rushConfiguration: this,
         splitWorkspaceCompatibility
       });
-      this._subspacesByName.set(subspaceName, subspace);
-      this._subspaces.push(subspace);
+      this.#subspacesByName.set(subspaceName, subspace);
+      this.#subspaces.push(subspace);
     }
-    const defaultSubspace: Subspace | undefined = this._subspacesByName.get(
+    const defaultSubspace: Subspace | undefined = this.#subspacesByName.get(
       RushConstants.defaultSubspaceName
     );
     if (!defaultSubspace) {
@@ -938,7 +938,7 @@ export class RushConfiguration {
       let subspace: Subspace | undefined = undefined;
       if (this.subspacesFeatureEnabled) {
         if (projectJson.subspaceName) {
-          subspace = this._subspacesByName.get(projectJson.subspaceName);
+          subspace = this.#subspacesByName.get(projectJson.subspaceName);
           if (subspace === undefined) {
             throw new Error(
               `The project "${projectJson.packageName}" in ${RushConstants.rushJsonFilename} references` +
@@ -960,17 +960,17 @@ export class RushConfiguration {
       });
       subspace._addProject(project);
 
-      this._projects.push(project);
-      if (this._projectsByName.has(project.packageName)) {
+      this.#projects.push(project);
+      if (this.#projectsByName.has(project.packageName)) {
         throw new Error(
           `The project name "${project.packageName}" was specified more than once` +
             ` in the ${RushConstants.rushJsonFilename} configuration file.`
         );
       }
-      this._projectsByName.set(project.packageName, project);
+      this.#projectsByName.set(project.packageName, project);
     }
 
-    for (const project of this._projects) {
+    for (const project of this.#projects) {
       project.decoupledLocalDependencies.forEach((decoupledLocalDependency: string) => {
         if (!this.getProjectByName(decoupledLocalDependency)) {
           throw new Error(
@@ -1191,11 +1191,11 @@ export class RushConfiguration {
   }
 
   public get projects(): RushConfigurationProject[] {
-    if (!this._projects) {
-      this._initializeAndValidateLocalProjects();
+    if (!this.#projects) {
+      this.#initializeAndValidateLocalProjects();
     }
 
-    return this._projects!;
+    return this.#projects!;
   }
 
   /**
@@ -1203,8 +1203,8 @@ export class RushConfiguration {
    */
   public get defaultSubspace(): Subspace {
     // TODO: Enable the default subspace to be obtained without initializing the full set of all projects
-    if (!this._projects) {
-      this._initializeAndValidateLocalProjects();
+    if (!this.#projects) {
+      this.#initializeAndValidateLocalProjects();
     }
     const defaultSubspace: Subspace | undefined = this.tryGetSubspace(RushConstants.defaultSubspaceName);
     if (!defaultSubspace) {
@@ -1218,20 +1218,20 @@ export class RushConfiguration {
    * @beta
    */
   public get subspaces(): readonly Subspace[] {
-    if (!this._projects) {
-      this._initializeAndValidateLocalProjects();
+    if (!this.#projects) {
+      this.#initializeAndValidateLocalProjects();
     }
-    return this._subspaces;
+    return this.#subspaces;
   }
 
   /**
    * @beta
    */
   public tryGetSubspace(subspaceName: string): Subspace | undefined {
-    if (!this._projects) {
-      this._initializeAndValidateLocalProjects();
+    if (!this.#projects) {
+      this.#initializeAndValidateLocalProjects();
     }
-    const subspace: Subspace | undefined = this._subspacesByName.get(subspaceName);
+    const subspace: Subspace | undefined = this.#subspacesByName.get(subspaceName);
     if (!subspace) {
       // If the name is not even valid, that is more important information than if the subspace doesn't exist
       SubspacesConfiguration.requireValidSubspaceName(
@@ -1258,8 +1258,8 @@ export class RushConfiguration {
    * @beta
    */
   public getSubspacesForProjects(projects: Iterable<RushConfigurationProject>): ReadonlySet<Subspace> {
-    if (!this._projects) {
-      this._initializeAndValidateLocalProjects();
+    if (!this.#projects) {
+      this.#initializeAndValidateLocalProjects();
     }
 
     const subspaceSet: Set<Subspace> = new Set();
@@ -1274,11 +1274,11 @@ export class RushConfiguration {
    * @beta
    */
   public get projectsByName(): ReadonlyMap<string, RushConfigurationProject> {
-    if (!this._projectsByName) {
-      this._initializeAndValidateLocalProjects();
+    if (!this.#projectsByName) {
+      this.#initializeAndValidateLocalProjects();
     }
 
-    return this._projectsByName!;
+    return this.#projectsByName!;
   }
 
   /**
@@ -1286,7 +1286,7 @@ export class RushConfiguration {
    * @beta
    */
   public get projectsByTag(): ReadonlyMap<string, ReadonlySet<RushConfigurationProject>> {
-    if (!this._projectsByTag) {
+    if (!this.#projectsByTag) {
       const projectsByTag: Map<string, Set<RushConfigurationProject>> = new Map();
       for (const project of this.projects) {
         for (const tag of project.tags) {
@@ -1297,9 +1297,9 @@ export class RushConfiguration {
           collection.add(project);
         }
       }
-      this._projectsByTag = projectsByTag;
+      this.#projectsByTag = projectsByTag;
     }
-    return this._projectsByTag;
+    return this.#projectsByTag;
   }
 
   /**
@@ -1324,7 +1324,7 @@ export class RushConfiguration {
    */
   public async getCurrentlyInstalledVariantAsync(): Promise<string | undefined> {
     if (!this._currentVariantJsonLoadingPromise) {
-      this._currentVariantJsonLoadingPromise = this._loadCurrentVariantJsonAsync();
+      this._currentVariantJsonLoadingPromise = this.#loadCurrentVariantJsonAsync();
     }
 
     return (await this._currentVariantJsonLoadingPromise)?.variant ?? undefined;
@@ -1445,9 +1445,9 @@ export class RushConfiguration {
    * @beta
    */
   public getProjectLookupForRoot(rootPath: string): LookupByPath<RushConfigurationProject> {
-    let pathTree: LookupByPath<RushConfigurationProject> | undefined = this._pathTrees.get(rootPath);
+    let pathTree: LookupByPath<RushConfigurationProject> | undefined = this.#pathTrees.get(rootPath);
     if (!pathTree) {
-      this._pathTrees.set(rootPath, (pathTree = new LookupByPath()));
+      this.#pathTrees.set(rootPath, (pathTree = new LookupByPath()));
       for (const project of this.projects) {
         const relativePath: string = path.relative(rootPath, project.projectFolder);
         pathTree.setItemFromSegments(LookupByPath.iteratePathSegments(relativePath, path.sep), project);
@@ -1474,7 +1474,7 @@ export class RushConfiguration {
     return undefined;
   }
 
-  private async _loadCurrentVariantJsonAsync(): Promise<ICurrentVariantJson | undefined> {
+  async #loadCurrentVariantJsonAsync(): Promise<ICurrentVariantJson | undefined> {
     try {
       return await JsonFile.loadAsync(this.currentVariantJsonFilePath);
     } catch (e) {
diff --git a/libraries/rush-lib/src/api/RushConfigurationProject.ts b/libraries/rush-lib/src/api/RushConfigurationProject.ts
index e80dce4bbde..505ce8cdcc3 100644
--- a/libraries/rush-lib/src/api/RushConfigurationProject.ts
+++ b/libraries/rush-lib/src/api/RushConfigurationProject.ts
@@ -66,12 +66,12 @@ export interface IRushConfigurationProjectOptions {
  * @public
  */
 export class RushConfigurationProject {
-  private readonly _shouldPublish: boolean;
+  readonly #shouldPublish: boolean;
 
-  private _versionPolicy: VersionPolicy | undefined = undefined;
-  private _dependencyProjects: Set<RushConfigurationProject> | undefined = undefined;
-  private _consumingProjects: Set<RushConfigurationProject> | undefined = undefined;
-  private _packageJson: IPackageJson;
+  #versionPolicy: VersionPolicy | undefined = undefined;
+  #dependencyProjects: Set<RushConfigurationProject> | undefined = undefined;
+  #consumingProjects: Set<RushConfigurationProject> | undefined = undefined;
+  #packageJson: IPackageJson;
 
   /**
    * The name of the NPM package.  An error is reported if this name is not
@@ -139,7 +139,7 @@ export class RushConfigurationProject {
    * The parsed NPM "package.json" file from projectFolder.
    */
   public get packageJson(): IPackageJson {
-    return this._packageJson;
+    return this.#packageJson;
   }
 
   /**
@@ -242,7 +242,7 @@ export class RushConfigurationProject {
     try {
       const packageJsonText: string = FileSystem.readFile(packageJsonFilename);
       // JSON.parse is native and runs in less than 1/2 the time of jju.parse. package.json is required to be strict JSON by NodeJS.
-      this._packageJson = JSON.parse(packageJsonText);
+      this.#packageJson = JSON.parse(packageJsonText);
     } catch (error) {
       if (FileSystem.isNotExistError(error as Error)) {
         throw new Error(`Could not find package.json for ${packageName} at ${packageJsonFilename}`);
@@ -300,8 +300,8 @@ export class RushConfigurationProject {
       filename: packageJsonFilename,
       onSaved: (newObject) => {
         // Just update the in-memory copy, don't bother doing the validation again
-        this._packageJson = newObject;
-        this._dependencyProjects = undefined; // Reset the cached dependency projects
+        this.#packageJson = newObject;
+        this.#dependencyProjects = undefined; // Reset the cached dependency projects
       }
     });
 
@@ -324,11 +324,11 @@ export class RushConfigurationProject {
         this.decoupledLocalDependencies.add(cyclicDependencyProject);
       }
     }
-    this._shouldPublish = !!projectJson.shouldPublish;
+    this.#shouldPublish = !!projectJson.shouldPublish;
     this.skipRushCheck = !!projectJson.skipRushCheck;
     this.versionPolicyName = projectJson.versionPolicyName;
 
-    if (this._shouldPublish && this.packageJson.private) {
+    if (this.#shouldPublish && this.packageJson.private) {
       throw new Error(
         `The project "${packageName}" specifies "shouldPublish": true, ` +
           `but the package.json file specifies "private": true.`
@@ -402,9 +402,9 @@ export class RushConfigurationProject {
    * referenced from this project.
    */
   public get dependencyProjects(): ReadonlySet<RushConfigurationProject> {
-    let dependencyProjects: Set<RushConfigurationProject> | undefined = this._dependencyProjects;
+    let dependencyProjects: Set<RushConfigurationProject> | undefined = this.#dependencyProjects;
     if (!dependencyProjects) {
-      this._dependencyProjects = dependencyProjects = new Set();
+      this.#dependencyProjects = dependencyProjects = new Set();
       const { packageJson } = this;
       for (const dependencySet of [
         packageJson.dependencies,
@@ -454,23 +454,23 @@ export class RushConfigurationProject {
    * graph to find all projects which will be impacted by changes to this project.
    */
   public get consumingProjects(): ReadonlySet<RushConfigurationProject> {
-    if (!this._consumingProjects) {
+    if (!this.#consumingProjects) {
       // Force initialize all dependency relationships
       // This needs to operate on every project in the set because the relationships are only specified
       // in the consuming project
       const { projects } = this.rushConfiguration;
 
       for (const project of projects) {
-        project._consumingProjects = new Set();
+        project.#consumingProjects = new Set();
       }
 
       for (const project of projects) {
         for (const dependency of project.dependencyProjects) {
-          dependency._consumingProjects!.add(project);
+          dependency.#consumingProjects!.add(project);
         }
       }
     }
-    return this._consumingProjects!;
+    return this.#consumingProjects!;
   }
 
   /**
@@ -479,7 +479,7 @@ export class RushConfigurationProject {
    * should be published during `rush publish`.
    */
   public get shouldPublish(): boolean {
-    return this._shouldPublish || !!this.versionPolicyName;
+    return this.#shouldPublish || !!this.versionPolicyName;
   }
 
   /**
@@ -487,14 +487,14 @@ export class RushConfigurationProject {
    * @beta
    */
   public get versionPolicy(): VersionPolicy | undefined {
-    if (!this._versionPolicy) {
+    if (!this.#versionPolicy) {
       if (this.versionPolicyName && this.rushConfiguration.versionPolicyConfiguration) {
-        this._versionPolicy = this.rushConfiguration.versionPolicyConfiguration.getVersionPolicy(
+        this.#versionPolicy = this.rushConfiguration.versionPolicyConfiguration.getVersionPolicy(
           this.versionPolicyName
         );
       }
     }
-    return this._versionPolicy;
+    return this.#versionPolicy;
   }
 
   /**
diff --git a/libraries/rush-lib/src/api/RushPluginsConfiguration.ts b/libraries/rush-lib/src/api/RushPluginsConfiguration.ts
index 9d3908fb601..7d67b2b6ebb 100644
--- a/libraries/rush-lib/src/api/RushPluginsConfiguration.ts
+++ b/libraries/rush-lib/src/api/RushPluginsConfiguration.ts
@@ -24,18 +24,18 @@ interface IRushPluginsConfigurationJson {
 const _jsonSchema: JsonSchema = JsonSchema.fromLoadedObject(schemaJson);
 
 export class RushPluginsConfiguration {
-  private _jsonFilename: string;
+  #jsonFilename: string;
 
   public readonly configuration: Readonly<IRushPluginsConfigurationJson>;
 
   public constructor(jsonFilename: string) {
-    this._jsonFilename = jsonFilename;
+    this.#jsonFilename = jsonFilename;
     this.configuration = {
       plugins: []
     };
 
-    if (FileSystem.exists(this._jsonFilename)) {
-      this.configuration = JsonFile.loadAndValidate(this._jsonFilename, _jsonSchema);
+    if (FileSystem.exists(this.#jsonFilename)) {
+      this.configuration = JsonFile.loadAndValidate(this.#jsonFilename, _jsonSchema);
     }
   }
 }
diff --git a/libraries/rush-lib/src/api/RushProjectConfiguration.ts b/libraries/rush-lib/src/api/RushProjectConfiguration.ts
index 50f71ce1785..ad877338b9b 100644
--- a/libraries/rush-lib/src/api/RushProjectConfiguration.ts
+++ b/libraries/rush-lib/src/api/RushProjectConfiguration.ts
@@ -299,7 +299,7 @@ export class RushProjectConfiguration {
 
   public readonly operationSettingsByOperationName: ReadonlyMap<string, Readonly<IOperationSettings>>;
 
-  private readonly _validationCache: WeakSet<object> = new WeakSet();
+  readonly #validationCache: WeakSet<object> = new WeakSet();
 
   private constructor(
     project: RushConfigurationProject,
@@ -321,7 +321,7 @@ export class RushProjectConfiguration {
    */
   public validatePhaseConfiguration(phases: Iterable<IPhase>, terminal: ITerminal): void {
     // Don't repeatedly validate the same set of phases for the same project.
-    if (this._validationCache.has(phases)) {
+    if (this.#validationCache.has(phases)) {
       return;
     }
 
@@ -397,7 +397,7 @@ export class RushProjectConfiguration {
       }
     }
 
-    this._validationCache.add(phases);
+    this.#validationCache.add(phases);
 
     if (hasErrors) {
       throw new AlreadyReportedError();
diff --git a/libraries/rush-lib/src/api/SaveCallbackPackageJsonEditor.ts b/libraries/rush-lib/src/api/SaveCallbackPackageJsonEditor.ts
index cf4f5028b47..9b319a4387c 100644
--- a/libraries/rush-lib/src/api/SaveCallbackPackageJsonEditor.ts
+++ b/libraries/rush-lib/src/api/SaveCallbackPackageJsonEditor.ts
@@ -12,12 +12,12 @@ export interface IFromObjectOptions {
 }
 
 export class SaveCallbackPackageJsonEditor extends PackageJsonEditor {
-  private readonly _onSaved: ((newObject: IPackageJson) => void) | undefined;
+  readonly #onSaved: ((newObject: IPackageJson) => void) | undefined;
 
   private constructor(options: IFromObjectOptions) {
     super(options.filename, options.object);
 
-    this._onSaved = options.onSaved;
+    this.#onSaved = options.onSaved;
   }
 
   public static fromObjectWithCallback(options: IFromObjectOptions): SaveCallbackPackageJsonEditor {
@@ -26,8 +26,8 @@ export class SaveCallbackPackageJsonEditor extends PackageJsonEditor {
 
   public override async saveIfModifiedAsync(): Promise<boolean> {
     const modified: boolean = await super.saveIfModifiedAsync();
-    if (this._onSaved) {
-      this._onSaved(this.saveToObject());
+    if (this.#onSaved) {
+      this.#onSaved(this.saveToObject());
     }
 
     return modified;
diff --git a/libraries/rush-lib/src/api/Subspace.ts b/libraries/rush-lib/src/api/Subspace.ts
index 49f00faa943..0f9583f9f7f 100644
--- a/libraries/rush-lib/src/api/Subspace.ts
+++ b/libraries/rush-lib/src/api/Subspace.ts
@@ -44,21 +44,21 @@ interface IPackageJsonLite extends Omit<IPackageJson, 'version'> {}
  */
 export class Subspace {
   public readonly subspaceName: string;
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _projects: RushConfigurationProject[] = [];
-  private readonly _splitWorkspaceCompatibility: boolean;
-  private _commonVersionsConfiguration: CommonVersionsConfiguration | undefined = undefined;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #projects: RushConfigurationProject[] = [];
+  readonly #splitWorkspaceCompatibility: boolean;
+  #commonVersionsConfiguration: CommonVersionsConfiguration | undefined = undefined;
 
-  private _detail: ISubspaceDetail | undefined;
+  #detail: ISubspaceDetail | undefined;
 
-  private _cachedPnpmOptions: PnpmOptionsConfiguration | undefined = undefined;
+  #cachedPnpmOptions: PnpmOptionsConfiguration | undefined = undefined;
   // If true, then _cachedPnpmOptions has been initialized.
-  private _cachedPnpmOptionsInitialized: boolean = false;
+  #cachedPnpmOptionsInitialized: boolean = false;
 
   public constructor(options: ISubspaceOptions) {
     this.subspaceName = options.subspaceName;
-    this._rushConfiguration = options.rushConfiguration;
-    this._splitWorkspaceCompatibility = options.splitWorkspaceCompatibility;
+    this.#rushConfiguration = options.rushConfiguration;
+    this.#splitWorkspaceCompatibility = options.splitWorkspaceCompatibility;
   }
 
   /**
@@ -66,7 +66,7 @@ export class Subspace {
    * @beta
    */
   public getProjects(): RushConfigurationProject[] {
-    return this._projects;
+    return this.#projects;
   }
 
   /**
@@ -74,19 +74,19 @@ export class Subspace {
    * @beta
    */
   public getPnpmOptions(): PnpmOptionsConfiguration | undefined {
-    if (!this._cachedPnpmOptionsInitialized) {
+    if (!this.#cachedPnpmOptionsInitialized) {
       // Calculate these outside the try/catch block since their error messages shouldn't be annotated:
       const subspaceTempFolder: string = this.getSubspaceTempFolderPath();
       try {
-        this._cachedPnpmOptions = PnpmOptionsConfiguration.loadFromJsonFileOrThrow(
+        this.#cachedPnpmOptions = PnpmOptionsConfiguration.loadFromJsonFileOrThrow(
           this.getPnpmConfigFilePath(),
           subspaceTempFolder
         );
-        this._cachedPnpmOptionsInitialized = true;
+        this.#cachedPnpmOptionsInitialized = true;
       } catch (e) {
         if (FileSystem.isNotExistError(e as Error)) {
-          this._cachedPnpmOptions = undefined;
-          this._cachedPnpmOptionsInitialized = true;
+          this.#cachedPnpmOptions = undefined;
+          this.#cachedPnpmOptionsInitialized = true;
         } else {
           throw new Error(
             `The subspace "${this.subspaceName}" has an invalid pnpm-config.json file:\n` + e.message
@@ -94,12 +94,12 @@ export class Subspace {
         }
       }
     }
-    return this._cachedPnpmOptions;
+    return this.#cachedPnpmOptions;
   }
 
-  private _ensureDetail(): ISubspaceDetail {
-    if (!this._detail) {
-      const rushConfiguration: RushConfiguration = this._rushConfiguration;
+  #ensureDetail(): ISubspaceDetail {
+    if (!this.#detail) {
+      const rushConfiguration: RushConfiguration = this.#rushConfiguration;
       let subspaceConfigFolderPath: string;
       let subspacePnpmPatchesFolderPath: string;
 
@@ -118,7 +118,7 @@ export class Subspace {
 
         subspaceConfigFolderPath = standardSubspaceConfigFolder;
 
-        if (this._splitWorkspaceCompatibility && this.subspaceName.startsWith('split_')) {
+        if (this.#splitWorkspaceCompatibility && this.subspaceName.startsWith('split_')) {
           if (FileSystem.exists(standardSubspaceConfigFolder + '/pnpm-lock.yaml')) {
             throw new Error(
               `The split workspace subspace "${this.subspaceName}" cannot use a common/config folder: ` +
@@ -126,13 +126,13 @@ export class Subspace {
             );
           }
 
-          if (this._projects.length !== 1) {
+          if (this.#projects.length !== 1) {
             throw new Error(
-              `The split workspace subspace "${this.subspaceName}" contains ${this._projects.length}` +
+              `The split workspace subspace "${this.subspaceName}" contains ${this.#projects.length}` +
                 ` projects; there must be exactly one project.`
             );
           }
-          const project: RushConfigurationProject = this._projects[0];
+          const project: RushConfigurationProject = this.#projects[0];
 
           subspaceConfigFolderPath = `${project.projectFolder}/subspace/${this.subspaceName}`;
 
@@ -184,7 +184,7 @@ export class Subspace {
       const parsedPath: path.ParsedPath = path.parse(tempShrinkwrapFilePath);
       const tempShrinkwrapPreinstallFilePath: string = `${parsedPath.dir}/${parsedPath.name}-preinstall${parsedPath.ext}`;
 
-      this._detail = {
+      this.#detail = {
         subspaceConfigFolderPath,
         subspacePnpmPatchesFolderPath,
         subspaceTempFolderPath,
@@ -192,7 +192,7 @@ export class Subspace {
         tempShrinkwrapPreinstallFilePath
       };
     }
-    return this._detail;
+    return this.#detail;
   }
 
   /**
@@ -228,7 +228,7 @@ export class Subspace {
    * @beta
    */
   public getSubspaceConfigFolderPath(): string {
-    return this._ensureDetail().subspaceConfigFolderPath;
+    return this.#ensureDetail().subspaceConfigFolderPath;
   }
 
   /**
@@ -239,7 +239,7 @@ export class Subspace {
    * @beta
    */
   public getSubspacePnpmPatchesFolderPath(): string {
-    return this._ensureDetail().subspacePnpmPatchesFolderPath;
+    return this.#ensureDetail().subspacePnpmPatchesFolderPath;
   }
 
   /**
@@ -250,7 +250,7 @@ export class Subspace {
    * @beta
    */
   public getSubspaceTempFolderPath(): string {
-    return this._ensureDetail().subspaceTempFolderPath;
+    return this.#ensureDetail().subspaceTempFolderPath;
   }
 
   /**
@@ -265,7 +265,7 @@ export class Subspace {
    * @beta
    */
   public getTempShrinkwrapFilename(): string {
-    return this._ensureDetail().tempShrinkwrapFilePath;
+    return this.#ensureDetail().tempShrinkwrapFilePath;
   }
 
   /**
@@ -286,7 +286,7 @@ export class Subspace {
    * @beta
    */
   public getTempShrinkwrapPreinstallFilePath(): string {
-    return this._ensureDetail().tempShrinkwrapPreinstallFilePath;
+    return this.#ensureDetail().tempShrinkwrapPreinstallFilePath;
   }
 
   /**
@@ -319,14 +319,14 @@ export class Subspace {
    */
   public getCommonVersions(variant?: string): CommonVersionsConfiguration {
     const commonVersionsFilePath: string = this.getCommonVersionsFilePath(variant);
-    if (!this._commonVersionsConfiguration) {
-      this._commonVersionsConfiguration = CommonVersionsConfiguration.loadFromFile(
+    if (!this.#commonVersionsConfiguration) {
+      this.#commonVersionsConfiguration = CommonVersionsConfiguration.loadFromFile(
         commonVersionsFilePath,
-        this._rushConfiguration
+        this.#rushConfiguration
       );
     }
 
-    return this._commonVersionsConfiguration;
+    return this.#commonVersionsConfiguration;
   }
 
   /**
@@ -343,7 +343,7 @@ export class Subspace {
 
     // Fallback to ensureConsistentVersions in rush.json if the setting is not defined in
     // the common-versions.json file
-    return this._rushConfiguration.ensureConsistentVersions;
+    return this.#rushConfiguration.ensureConsistentVersions;
   }
 
   /**
@@ -378,7 +378,7 @@ export class Subspace {
    */
   public getCommittedShrinkwrapFilePath(variant?: string): string {
     const subspaceConfigFolderPath: string = this.getVariantDependentSubspaceConfigFolderPath(variant);
-    return `${subspaceConfigFolderPath}/${this._rushConfiguration.shrinkwrapFilename}`;
+    return `${subspaceConfigFolderPath}/${this.#rushConfiguration.shrinkwrapFilename}`;
   }
 
   /**
@@ -391,7 +391,7 @@ export class Subspace {
   public getPnpmfilePath(variant?: string): string {
     const subspaceConfigFolderPath: string = this.getVariantDependentSubspaceConfigFolderPath(variant);
 
-    const pnpmFilename: string = (this._rushConfiguration.packageManagerWrapper as PnpmPackageManager)
+    const pnpmFilename: string = (this.#rushConfiguration.packageManagerWrapper as PnpmPackageManager)
       .pnpmfileFilename;
 
     return `${subspaceConfigFolderPath}/${pnpmFilename}`;
@@ -407,7 +407,7 @@ export class Subspace {
 
   /** @internal */
   public _addProject(project: RushConfigurationProject): void {
-    this._projects.push(project);
+    this.#projects.push(project);
   }
 
   /**
@@ -444,7 +444,7 @@ export class Subspace {
 
     const relatedProjects: RushConfigurationProject[] = [];
     const subspacePnpmfileShimSettings: ISubspacePnpmfileShimSettings =
-      SubspacePnpmfileConfiguration.getSubspacePnpmfileShimSettings(this._rushConfiguration, this, variant);
+      SubspacePnpmfileConfiguration.getSubspacePnpmfileShimSettings(this.#rushConfiguration, this, variant);
 
     for (const rushProject of this.getProjects()) {
       const injectedDependencies: Array<string> =
@@ -468,7 +468,7 @@ export class Subspace {
     }
 
     const allWorkspaceProjectSet: Set<string> = new Set(
-      this._rushConfiguration.projects.map((rushProject) => rushProject.packageName)
+      this.#rushConfiguration.projects.map((rushProject) => rushProject.packageName)
     );
 
     // get all related package.json
diff --git a/libraries/rush-lib/src/api/VersionPolicy.ts b/libraries/rush-lib/src/api/VersionPolicy.ts
index b738ba487d0..0266e61b2be 100644
--- a/libraries/rush-lib/src/api/VersionPolicy.ts
+++ b/libraries/rush-lib/src/api/VersionPolicy.ts
@@ -24,7 +24,7 @@ import { cloneDeep } from '../utilities/objectUtilities';
  * @internalRemarks
  * This is a copy of the semver ReleaseType enum, but with the `none` value added and
  * the `premajor` and `prepatch` omitted.
- * See {@link LockStepVersionPolicy._getReleaseType}.
+ * See `LockStepVersionPolicy.#getReleaseType`.
  *
  * TODO: Consider supporting `premajor` and `prepatch` in the future.
  */
@@ -124,11 +124,11 @@ export abstract class VersionPolicy {
    */
   public readonly _json: IVersionPolicyJson;
 
-  private get _versionFormatForCommit(): VersionFormatForCommit {
+  get #versionFormatForCommit(): VersionFormatForCommit {
     return this._json.dependencies?.versionFormatForCommit ?? 'original';
   }
 
-  private get _versionFormatForPublish(): VersionFormatForPublish {
+  get #versionFormatForPublish(): VersionFormatForPublish {
     return this._json.dependencies?.versionFormatForPublish ?? 'original';
   }
 
@@ -227,7 +227,7 @@ export abstract class VersionPolicy {
     const packageJsonEditor: PackageJsonEditor | undefined = updateDependenciesBeforePublish(
       packageName,
       configuration,
-      this._versionFormatForPublish
+      this.#versionFormatForPublish
     );
 
     packageJsonEditor?.saveIfModified();
@@ -244,7 +244,7 @@ export abstract class VersionPolicy {
     const packageJsonEditor: PackageJsonEditor | undefined = updateDependenciesBeforePublish(
       packageName,
       configuration,
-      this._versionFormatForPublish
+      this.#versionFormatForPublish
     );
 
     await packageJsonEditor?.saveIfModifiedAsync();
@@ -257,7 +257,7 @@ export abstract class VersionPolicy {
     const packageJsonEditor: PackageJsonEditor | undefined = updateDependenciesBeforeCommit(
       packageName,
       configuration,
-      this._versionFormatForCommit
+      this.#versionFormatForCommit
     );
 
     packageJsonEditor?.saveIfModified();
@@ -274,7 +274,7 @@ export abstract class VersionPolicy {
     const packageJsonEditor: PackageJsonEditor | undefined = updateDependenciesBeforeCommit(
       packageName,
       configuration,
-      this._versionFormatForCommit
+      this.#versionFormatForCommit
     );
 
     await packageJsonEditor?.saveIfModifiedAsync();
@@ -290,7 +290,7 @@ export class LockStepVersionPolicy extends VersionPolicy {
    * @internal
    */
   declare public readonly _json: ILockStepVersionJson;
-  private _version: semver.SemVer;
+  #version: semver.SemVer;
 
   /**
    * The type of bump for next bump.
@@ -316,14 +316,14 @@ export class LockStepVersionPolicy extends VersionPolicy {
    */
   public constructor(versionPolicyJson: ILockStepVersionJson) {
     super(versionPolicyJson);
-    this._version = new semver.SemVer(versionPolicyJson.version);
+    this.#version = new semver.SemVer(versionPolicyJson.version);
   }
 
   /**
    * The value of the lockstep version
    */
   public get version(): string {
-    return this._version.format();
+    return this.#version.format();
   }
 
   /**
@@ -334,16 +334,16 @@ export class LockStepVersionPolicy extends VersionPolicy {
    */
   public ensure(project: IPackageJson, force?: boolean): IPackageJson | undefined {
     const packageVersion: semver.SemVer = new semver.SemVer(project.version);
-    const compareResult: number = packageVersion.compare(this._version);
+    const compareResult: number = packageVersion.compare(this.#version);
     if (compareResult === 0) {
       return undefined;
     } else if (compareResult > 0 && !force) {
       const errorMessage: string =
         `Version ${project.version} in package ${project.name}` +
-        ` is higher than locked version ${this._version.format()}.`;
+        ` is higher than locked version ${this.#version.format()}.`;
       throw new Error(errorMessage);
     }
-    return this._updatePackageVersion(project, this._version);
+    return this.#updatePackageVersion(project, this.#version);
   }
 
   /**
@@ -360,7 +360,7 @@ export class LockStepVersionPolicy extends VersionPolicy {
       return;
     }
 
-    this._version.inc(this._getReleaseType(nextBump), identifier);
+    this.#version.inc(this.#getReleaseType(nextBump), identifier);
     this._json.version = this.version;
   }
 
@@ -370,10 +370,10 @@ export class LockStepVersionPolicy extends VersionPolicy {
    */
   public update(newVersionString: string): boolean {
     const newVersion: semver.SemVer = new semver.SemVer(newVersionString);
-    if (!newVersion || this._version === newVersion) {
+    if (!newVersion || this.#version === newVersion) {
       return false;
     }
-    this._version = newVersion;
+    this.#version = newVersion;
     this._json.version = this.version;
     return true;
   }
@@ -386,18 +386,18 @@ export class LockStepVersionPolicy extends VersionPolicy {
    */
   public validate(versionString: string, packageName: string): void {
     const versionToTest: semver.SemVer = new semver.SemVer(versionString, false);
-    if (this._version.compare(versionToTest) !== 0) {
+    if (this.#version.compare(versionToTest) !== 0) {
       throw new Error(`Invalid version ${versionString} in ${packageName}`);
     }
   }
 
-  private _updatePackageVersion(project: IPackageJson, newVersion: semver.SemVer): IPackageJson {
+  #updatePackageVersion(project: IPackageJson, newVersion: semver.SemVer): IPackageJson {
     const updatedProject: IPackageJson = cloneDeep(project);
     updatedProject.version = newVersion.format();
     return updatedProject;
   }
 
-  private _getReleaseType(bumpType: BumpType): semver.ReleaseType {
+  #getReleaseType(bumpType: BumpType): semver.ReleaseType {
     // Eventually we should just use ReleaseType and get rid of bump type.
     return BumpType[bumpType] as semver.ReleaseType;
   }
diff --git a/libraries/rush-lib/src/api/VersionPolicyConfiguration.ts b/libraries/rush-lib/src/api/VersionPolicyConfiguration.ts
index 16d1804561c..a96f230c3cf 100644
--- a/libraries/rush-lib/src/api/VersionPolicyConfiguration.ts
+++ b/libraries/rush-lib/src/api/VersionPolicyConfiguration.ts
@@ -71,7 +71,7 @@ const _jsonSchema: JsonSchema = JsonSchema.fromLoadedObject(schemaJson);
  * @public
  */
 export class VersionPolicyConfiguration {
-  private _jsonFileName: string;
+  #jsonFileName: string;
 
   /**
    * Gets all the version policies
@@ -82,9 +82,9 @@ export class VersionPolicyConfiguration {
    * @internal
    */
   public constructor(jsonFileName: string) {
-    this._jsonFileName = jsonFileName;
+    this.#jsonFileName = jsonFileName;
     this.versionPolicies = new Map<string, VersionPolicy>();
-    this._loadFile();
+    this.#loadFile();
   }
 
   /**
@@ -144,7 +144,7 @@ export class VersionPolicyConfiguration {
         }
       });
     }
-    this._saveFile(!!shouldCommit);
+    this.#saveFile(!!shouldCommit);
   }
 
   /**
@@ -162,15 +162,15 @@ export class VersionPolicyConfiguration {
     if (lockStepVersionPolicy.update(newVersion)) {
       // eslint-disable-next-line no-console
       console.log(`\nUpdate version policy ${versionPolicyName} from ${previousVersion} to ${newVersion}`);
-      this._saveFile(!!shouldCommit);
+      this.#saveFile(!!shouldCommit);
     }
   }
 
-  private _loadFile(): void {
-    if (!FileSystem.exists(this._jsonFileName)) {
+  #loadFile(): void {
+    if (!FileSystem.exists(this.#jsonFileName)) {
       return;
     }
-    const versionPolicyJson: IVersionPolicyJson[] = JsonFile.loadAndValidate(this._jsonFileName, _jsonSchema);
+    const versionPolicyJson: IVersionPolicyJson[] = JsonFile.loadAndValidate(this.#jsonFileName, _jsonSchema);
 
     versionPolicyJson.forEach((policyJson) => {
       const policy: VersionPolicy | undefined = VersionPolicy.load(policyJson);
@@ -180,13 +180,13 @@ export class VersionPolicyConfiguration {
     });
   }
 
-  private _saveFile(shouldCommit: boolean): void {
+  #saveFile(shouldCommit: boolean): void {
     const versionPolicyJson: IVersionPolicyJson[] = [];
     this.versionPolicies.forEach((versionPolicy) => {
       versionPolicyJson.push(versionPolicy._json);
     });
     if (shouldCommit) {
-      JsonFile.save(versionPolicyJson, this._jsonFileName, { updateExistingFile: true });
+      JsonFile.save(versionPolicyJson, this.#jsonFileName, { updateExistingFile: true });
     }
   }
 }
diff --git a/libraries/rush-lib/src/cli/RushCommandLineParser.ts b/libraries/rush-lib/src/cli/RushCommandLineParser.ts
index 47f2b3a640b..1546b9cce3e 100644
--- a/libraries/rush-lib/src/cli/RushCommandLineParser.ts
+++ b/libraries/rush-lib/src/cli/RushCommandLineParser.ts
@@ -81,19 +81,19 @@ export class RushCommandLineParser extends CommandLineParser {
   public readonly rushSession: RushSession;
   public readonly pluginManager: PluginManager;
 
-  private readonly _debugParameter: CommandLineFlagParameter;
-  private readonly _quietParameter: CommandLineFlagParameter;
-  private readonly _restrictConsoleOutput: boolean = RushCommandLineParser.shouldRestrictConsoleOutput();
-  private readonly _rushOptions: IRushCommandLineParserOptions;
-  private readonly _terminalProvider: ConsoleTerminalProvider;
-  private readonly _terminal: Terminal;
-  private readonly _autocreateBuildCommand: boolean;
+  readonly #debugParameter: CommandLineFlagParameter;
+  readonly #quietParameter: CommandLineFlagParameter;
+  readonly #restrictConsoleOutput: boolean = RushCommandLineParser.shouldRestrictConsoleOutput();
+  readonly #rushOptions: IRushCommandLineParserOptions;
+  readonly #terminalProvider: ConsoleTerminalProvider;
+  readonly #terminal: Terminal;
+  readonly #autocreateBuildCommand: boolean;
 
   /**
    * The current working directory that was used to find the Rush configuration.
    */
   public get cwd(): string {
-    return this._rushOptions.cwd;
+    return this.#rushOptions.cwd;
   }
 
   public constructor(options?: Partial<IRushCommandLineParserOptions>) {
@@ -111,30 +111,30 @@ export class RushCommandLineParser extends CommandLineParser {
       enableTabCompletionAction: true
     });
 
-    this._debugParameter = this.defineFlagParameter({
+    this.#debugParameter = this.defineFlagParameter({
       parameterLongName: '--debug',
       parameterShortName: '-d',
       description: 'Show the full call stack if an error occurs while executing the tool'
     });
 
-    this._quietParameter = this.defineFlagParameter({
+    this.#quietParameter = this.defineFlagParameter({
       parameterLongName: '--quiet',
       parameterShortName: '-q',
       description: 'Hide rush startup information'
     });
 
     const terminalProvider: ConsoleTerminalProvider = new ConsoleTerminalProvider();
-    this._terminalProvider = terminalProvider;
-    const terminal: Terminal = new Terminal(this._terminalProvider);
-    this._terminal = terminal;
-    this._rushOptions = this._normalizeOptions(options || {});
-    const { cwd, alreadyReportedNodeTooNewError, builtInPluginConfigurations } = this._rushOptions;
+    this.#terminalProvider = terminalProvider;
+    const terminal: Terminal = new Terminal(this.#terminalProvider);
+    this.#terminal = terminal;
+    this.#rushOptions = this.#normalizeOptions(options || {});
+    const { cwd, alreadyReportedNodeTooNewError, builtInPluginConfigurations } = this.#rushOptions;
 
     let rushJsonFilePath: string | undefined;
     try {
       rushJsonFilePath = RushConfiguration.tryFindRushJsonLocation({
         startingFolder: cwd,
-        showVerbose: !this._restrictConsoleOutput
+        showVerbose: !this.#restrictConsoleOutput
       });
 
       initializeDotEnv(terminal, rushJsonFilePath);
@@ -163,7 +163,7 @@ export class RushCommandLineParser extends CommandLineParser {
       rushConfiguration: this.rushConfiguration,
       terminal,
       builtInPluginConfigurations,
-      restrictConsoleOutput: this._restrictConsoleOutput,
+      restrictConsoleOutput: this.#restrictConsoleOutput,
       rushGlobalFolder: this.rushGlobalFolder
     });
 
@@ -175,13 +175,13 @@ export class RushCommandLineParser extends CommandLineParser {
     );
 
     // If the plugin has a build command, we don't need to autocreate the default build command.
-    this._autocreateBuildCommand = !hasBuildCommandInPlugin;
+    this.#autocreateBuildCommand = !hasBuildCommandInPlugin;
 
-    this._populateActions();
+    this.#populateActions();
 
     for (const { commandLineConfiguration, pluginLoader } of pluginCommandLineConfigurations) {
       try {
-        this._addCommandLineConfigActions(commandLineConfiguration);
+        this.#addCommandLineConfigActions(commandLineConfiguration);
       } catch (e) {
         this._reportErrorAndSetExitCode(
           new Error(
@@ -195,15 +195,15 @@ export class RushCommandLineParser extends CommandLineParser {
   }
 
   public get isDebug(): boolean {
-    return this._debugParameter.value;
+    return this.#debugParameter.value;
   }
 
   public get isQuiet(): boolean {
-    return this._quietParameter.value;
+    return this.#quietParameter.value;
   }
 
   public get terminal(): ITerminal {
-    return this._terminal;
+    return this.#terminal;
   }
 
   /**
@@ -235,7 +235,7 @@ export class RushCommandLineParser extends CommandLineParser {
 
   public override async executeAsync(args?: string[]): Promise<boolean> {
     // debugParameter will be correctly parsed during super.executeAsync(), so manually parse here.
-    this._terminalProvider.verboseEnabled = this._terminalProvider.debugEnabled =
+    this.#terminalProvider.verboseEnabled = this.#terminalProvider.debugEnabled =
       process.argv.indexOf('--debug') >= 0;
 
     await measureAsyncFn('rush:initializeUnassociatedPlugins', () =>
@@ -253,12 +253,12 @@ export class RushCommandLineParser extends CommandLineParser {
     // -- if it falsely appears to succeed, we could merge bad PRs, publish empty packages, etc.
     process.exitCode = 1;
 
-    if (this._debugParameter.value) {
+    if (this.#debugParameter.value) {
       InternalError.breakInDebugger = true;
     }
 
     try {
-      await this._wrapOnExecuteAsync();
+      await this.#wrapOnExecuteAsync();
 
       // TODO: rushConfiguration is typed as "!: RushConfiguration" here, but can sometimes be undefined
       if (this.rushConfiguration) {
@@ -274,10 +274,10 @@ export class RushCommandLineParser extends CommandLineParser {
 
             // only display alerts when certain specific actions are triggered
             if (RushAlerts.alertTriggerActions.includes(actionName)) {
-              this._terminal.writeDebugLine('Checking Rush alerts...');
+              this.#terminal.writeDebugLine('Checking Rush alerts...');
               const rushAlerts: RushAlerts = await RushAlerts.loadFromConfigurationAsync(
                 this.rushConfiguration,
-                this._terminal
+                this.#terminal
               );
               // Print out alerts if have after each successful command actions
               await rushAlerts.printAlertsAsync();
@@ -289,8 +289,8 @@ export class RushCommandLineParser extends CommandLineParser {
           }
           // Generally the RushAlerts implementation should handle its own error reporting; if not,
           // clarify the source, since the Rush Alerts behavior is nondeterministic and may not repro easily:
-          this._terminal.writeErrorLine(`\nAn unexpected error was encountered by the Rush alerts feature:`);
-          this._terminal.writeErrorLine(error.message);
+          this.#terminal.writeErrorLine(`\nAn unexpected error was encountered by the Rush alerts feature:`);
+          this.#terminal.writeErrorLine(error.message);
           throw new AlreadyReportedError();
         }
       }
@@ -305,7 +305,7 @@ export class RushCommandLineParser extends CommandLineParser {
     await this.telemetry?.ensureFlushedAsync();
   }
 
-  private _normalizeOptions(options: Partial<IRushCommandLineParserOptions>): IRushCommandLineParserOptions {
+  #normalizeOptions(options: Partial<IRushCommandLineParserOptions>): IRushCommandLineParserOptions {
     return {
       cwd: options.cwd || process.cwd(),
       alreadyReportedNodeTooNewError: options.alreadyReportedNodeTooNewError || false,
@@ -313,7 +313,7 @@ export class RushCommandLineParser extends CommandLineParser {
     };
   }
 
-  private async _wrapOnExecuteAsync(): Promise<void> {
+  async #wrapOnExecuteAsync(): Promise<void> {
     if (this.rushConfiguration) {
       this.telemetry = new Telemetry(this.rushConfiguration, this.rushSession);
     }
@@ -327,7 +327,7 @@ export class RushCommandLineParser extends CommandLineParser {
     }
   }
 
-  private _populateActions(): void {
+  #populateActions(): void {
     try {
       // Alphabetical order
       this.addAction(new AddAction(this));
@@ -357,13 +357,13 @@ export class RushCommandLineParser extends CommandLineParser {
       this.addAction(new BridgePackageAction(this));
       this.addAction(new LinkPackageAction(this));
 
-      this._populateScriptActions();
+      this.#populateScriptActions();
     } catch (error) {
       this._reportErrorAndSetExitCode(error as Error);
     }
   }
 
-  private _populateScriptActions(): void {
+  #populateScriptActions(): void {
     // If there is not a rush.json file, we still want "build" and "rebuild" to appear in the
     // command-line help
     let commandLineConfigFilePath: string | undefined;
@@ -375,23 +375,23 @@ export class RushCommandLineParser extends CommandLineParser {
     }
 
     // If a build action is already added by a plugin, we don't want to add a default "build" script
-    const doNotIncludeDefaultBuildCommands: boolean = !this._autocreateBuildCommand;
+    const doNotIncludeDefaultBuildCommands: boolean = !this.#autocreateBuildCommand;
 
     const commandLineConfiguration: CommandLineConfiguration = CommandLineConfiguration.loadFromFileOrDefault(
       commandLineConfigFilePath,
       doNotIncludeDefaultBuildCommands
     );
-    this._addCommandLineConfigActions(commandLineConfiguration);
+    this.#addCommandLineConfigActions(commandLineConfiguration);
   }
 
-  private _addCommandLineConfigActions(commandLineConfiguration: CommandLineConfiguration): void {
+  #addCommandLineConfigActions(commandLineConfiguration: CommandLineConfiguration): void {
     // Register each custom command
     for (const command of commandLineConfiguration.commands.values()) {
-      this._addCommandLineConfigAction(commandLineConfiguration, command);
+      this.#addCommandLineConfigAction(commandLineConfiguration, command);
     }
   }
 
-  private _addCommandLineConfigAction(
+  #addCommandLineConfigAction(
     commandLineConfiguration: CommandLineConfiguration,
     command: Command
   ): void {
@@ -404,12 +404,12 @@ export class RushCommandLineParser extends CommandLineParser {
 
     switch (command.commandKind) {
       case RushConstants.globalCommandKind: {
-        this._addGlobalScriptAction(commandLineConfiguration, command);
+        this.#addGlobalScriptAction(commandLineConfiguration, command);
         break;
       }
 
       case RushConstants.phasedCommandKind: {
-        this._addPhasedCommandLineConfigAction(commandLineConfiguration, command);
+        this.#addPhasedCommandLineConfigAction(commandLineConfiguration, command);
         break;
       }
 
@@ -421,7 +421,7 @@ export class RushCommandLineParser extends CommandLineParser {
     }
   }
 
-  private _getSharedCommandActionOptions<TCommand extends Command>(
+  #getSharedCommandActionOptions<TCommand extends Command>(
     commandLineConfiguration: CommandLineConfiguration,
     command: TCommand
   ): IBaseScriptActionOptions<TCommand> {
@@ -437,7 +437,7 @@ export class RushCommandLineParser extends CommandLineParser {
     };
   }
 
-  private _addGlobalScriptAction(
+  #addGlobalScriptAction(
     commandLineConfiguration: CommandLineConfiguration,
     command: IGlobalCommandConfig
   ): void {
@@ -452,7 +452,7 @@ export class RushCommandLineParser extends CommandLineParser {
     }
 
     const sharedCommandOptions: IBaseScriptActionOptions<IGlobalCommandConfig> =
-      this._getSharedCommandActionOptions(commandLineConfiguration, command);
+      this.#getSharedCommandActionOptions(commandLineConfiguration, command);
 
     this.addAction(
       new GlobalScriptAction({
@@ -465,12 +465,12 @@ export class RushCommandLineParser extends CommandLineParser {
     );
   }
 
-  private _addPhasedCommandLineConfigAction(
+  #addPhasedCommandLineConfigAction(
     commandLineConfiguration: CommandLineConfiguration,
     command: IPhasedCommandConfig
   ): void {
     const baseCommandOptions: IBaseScriptActionOptions<IPhasedCommandConfig> =
-      this._getSharedCommandActionOptions(commandLineConfiguration, command);
+      this.#getSharedCommandActionOptions(commandLineConfiguration, command);
 
     const {
       enableParallelism,
@@ -525,7 +525,7 @@ export class RushCommandLineParser extends CommandLineParser {
       console.error(`\n${message}`);
     }
 
-    if (this._debugParameter.value) {
+    if (this.#debugParameter.value) {
       // If catchSyncErrors() called this, then show a call stack similar to what Node.js
       // would show for an uncaught error
       // eslint-disable-next-line no-console
diff --git a/libraries/rush-lib/src/cli/actions/AddAction.ts b/libraries/rush-lib/src/cli/actions/AddAction.ts
index db67f19ea0c..5eb0784c65f 100644
--- a/libraries/rush-lib/src/cli/actions/AddAction.ts
+++ b/libraries/rush-lib/src/cli/actions/AddAction.ts
@@ -22,11 +22,11 @@ const EXACT_FLAG_NAME: '--exact' = '--exact';
 const CARET_FLAG_NAME: '--caret' = '--caret';
 
 export class AddAction extends BaseAddAndRemoveAction {
-  private readonly _exactFlag: CommandLineFlagParameter;
-  private readonly _caretFlag: CommandLineFlagParameter;
-  private readonly _devDependencyFlag: CommandLineFlagParameter;
-  private readonly _peerDependencyFlag: CommandLineFlagParameter;
-  private readonly _makeConsistentFlag: CommandLineFlagParameter;
+  readonly #exactFlag: CommandLineFlagParameter;
+  readonly #caretFlag: CommandLineFlagParameter;
+  readonly #devDependencyFlag: CommandLineFlagParameter;
+  readonly #peerDependencyFlag: CommandLineFlagParameter;
+  readonly #makeConsistentFlag: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     const documentation: string = [
@@ -52,29 +52,29 @@ export class AddAction extends BaseAddAndRemoveAction {
         ` To add multiple packages, write "rush add ${PACKAGE_PARAMETER_NAME} foo ${PACKAGE_PARAMETER_NAME} bar".`
     });
 
-    this._exactFlag = this.defineFlagParameter({
+    this.#exactFlag = this.defineFlagParameter({
       parameterLongName: EXACT_FLAG_NAME,
       description:
         'If specified, the SemVer specifier added to the' +
         ' package.json will be an exact version (e.g. without tilde or caret).'
     });
-    this._caretFlag = this.defineFlagParameter({
+    this.#caretFlag = this.defineFlagParameter({
       parameterLongName: CARET_FLAG_NAME,
       description:
         'If specified, the SemVer specifier added to the' +
         ' package.json will be a prepended with a "caret" specifier ("^").'
     });
-    this._devDependencyFlag = this.defineFlagParameter({
+    this.#devDependencyFlag = this.defineFlagParameter({
       parameterLongName: '--dev',
       description:
         'If specified, the package will be added to the "devDependencies" section of the package.json'
     });
-    this._peerDependencyFlag = this.defineFlagParameter({
+    this.#peerDependencyFlag = this.defineFlagParameter({
       parameterLongName: '--peer',
       description:
         'If specified, the package will be added to the "peerDependencies" section of the package.json'
     });
-    this._makeConsistentFlag = this.defineFlagParameter({
+    this.#makeConsistentFlag = this.defineFlagParameter({
       parameterLongName: MAKE_CONSISTENT_FLAG_NAME,
       parameterShortName: '-m',
       description:
@@ -86,9 +86,9 @@ export class AddAction extends BaseAddAndRemoveAction {
   public async getUpdateOptionsAsync(): Promise<IPackageJsonUpdaterRushAddOptions> {
     const projects: RushConfigurationProject[] = super.getProjects();
 
-    if (this._caretFlag.value && this._exactFlag.value) {
+    if (this.#caretFlag.value && this.#exactFlag.value) {
       throw new Error(
-        `Only one of "${this._caretFlag.longName}" and "${this._exactFlag.longName}" should be specified`
+        `Only one of "${this.#caretFlag.longName}" and "${this.#exactFlag.longName}" should be specified`
       );
     }
 
@@ -127,18 +127,18 @@ export class AddAction extends BaseAddAndRemoveAction {
        */
       let rangeStyle: SemVerStyle;
       if (version && version !== 'latest') {
-        if (this._exactFlag.value || this._caretFlag.value) {
+        if (this.#exactFlag.value || this.#caretFlag.value) {
           throw new Error(
-            `The "${this._caretFlag.longName}" and "${this._exactFlag.longName}" flags may not be specified if a ` +
+            `The "${this.#caretFlag.longName}" and "${this.#exactFlag.longName}" flags may not be specified if a ` +
               `version is provided in the ${this._packageNameListParameter.longName} specifier. In this case "${version}" was provided.`
           );
         }
 
         rangeStyle = SemVerStyle.Passthrough;
       } else {
-        rangeStyle = this._caretFlag.value
+        rangeStyle = this.#caretFlag.value
           ? SemVerStyle.Caret
-          : this._exactFlag.value
+          : this.#exactFlag.value
             ? SemVerStyle.Exact
             : SemVerStyle.Tilde;
       }
@@ -155,9 +155,9 @@ export class AddAction extends BaseAddAndRemoveAction {
     return {
       projects,
       packagesToUpdate: packagesToAdd,
-      devDependency: this._devDependencyFlag.value,
-      peerDependency: this._peerDependencyFlag.value,
-      updateOtherPackages: this._makeConsistentFlag.value,
+      devDependency: this.#devDependencyFlag.value,
+      peerDependency: this.#peerDependencyFlag.value,
+      updateOtherPackages: this.#makeConsistentFlag.value,
       skipUpdate: this._skipUpdateFlag.value,
       debugInstall: this.parser.isDebug,
       actionName: this.actionName,
diff --git a/libraries/rush-lib/src/cli/actions/AlertAction.ts b/libraries/rush-lib/src/cli/actions/AlertAction.ts
index 052220c06b0..5a56e637dce 100644
--- a/libraries/rush-lib/src/cli/actions/AlertAction.ts
+++ b/libraries/rush-lib/src/cli/actions/AlertAction.ts
@@ -8,8 +8,8 @@ import { BaseRushAction } from './BaseRushAction';
 import { RushAlerts } from '../../utilities/RushAlerts';
 
 export class AlertAction extends BaseRushAction {
-  private readonly _snoozeParameter: CommandLineStringParameter;
-  private readonly _snoozeTimeFlagParameter: CommandLineFlagParameter;
+  readonly #snoozeParameter: CommandLineStringParameter;
+  readonly #snoozeTimeFlagParameter: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -22,14 +22,14 @@ export class AlertAction extends BaseRushAction {
       parser
     });
 
-    this._snoozeParameter = this.defineStringParameter({
+    this.#snoozeParameter = this.defineStringParameter({
       parameterLongName: '--snooze',
       parameterShortName: '-s',
       argumentName: 'ALERT_ID',
       description: 'Temporarily suspend the specified alert for one week'
     });
 
-    this._snoozeTimeFlagParameter = this.defineFlagParameter({
+    this.#snoozeTimeFlagParameter = this.defineFlagParameter({
       parameterLongName: '--forever',
       description: 'Combined with "--snooze", causes that alert to be suspended permanently'
     });
@@ -40,9 +40,9 @@ export class AlertAction extends BaseRushAction {
       this.rushConfiguration,
       this.terminal
     );
-    const snoozeAlertId: string | undefined = this._snoozeParameter.value;
+    const snoozeAlertId: string | undefined = this.#snoozeParameter.value;
     if (snoozeAlertId) {
-      const snoozeTimeFlag: boolean = this._snoozeTimeFlagParameter.value;
+      const snoozeTimeFlag: boolean = this.#snoozeTimeFlagParameter.value;
       await rushAlerts.snoozeAlertsByAlertIdAsync(snoozeAlertId, snoozeTimeFlag);
     }
     await rushAlerts.printAllAlertsAsync();
diff --git a/libraries/rush-lib/src/cli/actions/BaseInstallAction.ts b/libraries/rush-lib/src/cli/actions/BaseInstallAction.ts
index b13b34fe681..2f0c9f9b447 100644
--- a/libraries/rush-lib/src/cli/actions/BaseInstallAction.ts
+++ b/libraries/rush-lib/src/cli/actions/BaseInstallAction.ts
@@ -269,7 +269,7 @@ export abstract class BaseInstallAction extends BaseRushAction {
             };
           }
 
-          await this._doInstallAsync(
+          await this.#doInstallAsync(
             installManagerFactoryModule,
             purgeManager,
             installManagerOptionsForInstall
@@ -277,7 +277,7 @@ export abstract class BaseInstallAction extends BaseRushAction {
         }
       } else {
         // Simple case when subspacesFeatureEnabled=false
-        await this._doInstallAsync(installManagerFactoryModule, purgeManager, {
+        await this.#doInstallAsync(installManagerFactoryModule, purgeManager, {
           ...installManagerOptions,
           subspace: this.rushConfiguration.defaultSubspace
         });
@@ -291,7 +291,7 @@ export abstract class BaseInstallAction extends BaseRushAction {
       );
       stopwatch.stop();
 
-      this._collectTelemetry(stopwatch, installManagerOptions, installSuccessful);
+      this.#collectTelemetry(stopwatch, installManagerOptions, installSuccessful);
       this.parser.flushTelemetry();
       this.eventHooksManager.handle(
         Event.postRushInstall,
@@ -317,7 +317,7 @@ export abstract class BaseInstallAction extends BaseRushAction {
     );
   }
 
-  private async _doInstallAsync(
+  async #doInstallAsync(
     installManagerFactoryModule: typeof import('../../logic/InstallManagerFactory'),
     purgeManager: PurgeManager,
     installManagerOptions: IInstallManagerOptions
@@ -333,7 +333,7 @@ export abstract class BaseInstallAction extends BaseRushAction {
     await measureAsyncFn('rush:installManager:doInstallAsync', () => installManager.doInstallAsync());
   }
 
-  private _collectTelemetry(
+  #collectTelemetry(
     stopwatch: Stopwatch,
     installManagerOptions: Omit<IInstallManagerOptions, 'subspace'>,
     success: boolean
diff --git a/libraries/rush-lib/src/cli/actions/BaseRushAction.ts b/libraries/rush-lib/src/cli/actions/BaseRushAction.ts
index 256224d10f4..fc92b4ac237 100644
--- a/libraries/rush-lib/src/cli/actions/BaseRushAction.ts
+++ b/libraries/rush-lib/src/cli/actions/BaseRushAction.ts
@@ -39,7 +39,7 @@ export interface IBaseRushActionOptions extends ICommandLineActionOptions {
  * can be used without a rush.json configuration.
  */
 export abstract class BaseConfiglessRushAction extends CommandLineAction implements IRushCommand {
-  private _safeForSimultaneousRushProcesses: boolean;
+  #safeForSimultaneousRushProcesses: boolean;
 
   protected readonly rushConfiguration: RushConfiguration | undefined;
   protected readonly terminal: ITerminal;
@@ -53,7 +53,7 @@ export abstract class BaseConfiglessRushAction extends CommandLineAction impleme
     const { parser, safeForSimultaneousRushProcesses } = options;
     this.parser = parser;
     const { rushConfiguration, terminal, rushSession, rushGlobalFolder } = parser;
-    this._safeForSimultaneousRushProcesses = !!safeForSimultaneousRushProcesses;
+    this.#safeForSimultaneousRushProcesses = !!safeForSimultaneousRushProcesses;
     this.rushConfiguration = rushConfiguration;
     this.terminal = terminal;
     this.rushSession = rushSession;
@@ -61,10 +61,10 @@ export abstract class BaseConfiglessRushAction extends CommandLineAction impleme
   }
 
   protected override async onExecuteAsync(): Promise<void> {
-    this._ensureEnvironment();
+    this.#ensureEnvironment();
 
     if (this.rushConfiguration) {
-      if (!this._safeForSimultaneousRushProcesses) {
+      if (!this.#safeForSimultaneousRushProcesses) {
         if (!LockFile.tryAcquire(this.rushConfiguration.commonTempFolder, 'rush')) {
           this.terminal.writeLine(
             Colorize.red(`Another Rush command is already running in this repository.`)
@@ -87,7 +87,7 @@ export abstract class BaseConfiglessRushAction extends CommandLineAction impleme
    */
   protected abstract runAsync(): Promise<void>;
 
-  private _ensureEnvironment(): void {
+  #ensureEnvironment(): void {
     if (this.rushConfiguration) {
       // eslint-disable-next-line dot-notation
       let environmentPath: string | undefined = process.env['PATH'];
@@ -105,14 +105,14 @@ export abstract class BaseConfiglessRushAction extends CommandLineAction impleme
  * The base class that most Rush command-line actions should extend.
  */
 export abstract class BaseRushAction extends BaseConfiglessRushAction {
-  private _eventHooksManager: EventHooksManager | undefined;
+  #eventHooksManager: EventHooksManager | undefined;
 
   protected get eventHooksManager(): EventHooksManager {
-    if (!this._eventHooksManager) {
-      this._eventHooksManager = new EventHooksManager(this.rushConfiguration);
+    if (!this.#eventHooksManager) {
+      this.#eventHooksManager = new EventHooksManager(this.rushConfiguration);
     }
 
-    return this._eventHooksManager;
+    return this.#eventHooksManager;
   }
 
   protected declare readonly rushConfiguration: RushConfiguration;
@@ -122,13 +122,13 @@ export abstract class BaseRushAction extends BaseConfiglessRushAction {
       throw Utilities.getRushConfigNotFoundError();
     }
 
-    this._throwPluginErrorIfNeed();
+    this.#throwPluginErrorIfNeed();
 
     await measureAsyncFn(`${PERF_PREFIX}:initializePluginsAsync`, () =>
       this.parser.pluginManager.tryInitializeAssociatedCommandPluginsAsync(this.actionName)
     );
 
-    this._throwPluginErrorIfNeed();
+    this.#throwPluginErrorIfNeed();
 
     const { hooks: sessionHooks } = this.rushSession;
     await measureAsyncFn(`${PERF_PREFIX}:initializePlugins`, async () => {
@@ -145,7 +145,7 @@ export abstract class BaseRushAction extends BaseConfiglessRushAction {
    * If an error is encountered while trying to load plugins, it is saved in the `PluginManager.error`
    * property, so we can defer throwing it until when `_throwPluginErrorIfNeed()` is called.
    */
-  private _throwPluginErrorIfNeed(): void {
+  #throwPluginErrorIfNeed(): void {
     // If the plugin configuration is broken, these three commands are used to fix the problem:
     //
     //   "rush update"
diff --git a/libraries/rush-lib/src/cli/actions/BridgePackageAction.ts b/libraries/rush-lib/src/cli/actions/BridgePackageAction.ts
index a380251c099..029ef34e34c 100644
--- a/libraries/rush-lib/src/cli/actions/BridgePackageAction.ts
+++ b/libraries/rush-lib/src/cli/actions/BridgePackageAction.ts
@@ -16,8 +16,8 @@ import type { Subspace } from '../../api/Subspace';
 import type { RushConfigurationProject } from '../../api/RushConfigurationProject';
 
 export class BridgePackageAction extends BaseHotlinkPackageAction {
-  private readonly _versionParameter: IRequiredCommandLineStringParameter;
-  private readonly _subspaceNamesParameter: CommandLineStringListParameter;
+  readonly #versionParameter: IRequiredCommandLineStringParameter;
+  readonly #subspaceNamesParameter: CommandLineStringListParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -35,23 +35,23 @@ export class BridgePackageAction extends BaseHotlinkPackageAction {
       parser
     });
 
-    this._versionParameter = this.defineStringParameter({
+    this.#versionParameter = this.defineStringParameter({
       parameterLongName: '--version',
       argumentName: 'SEMVER_RANGE',
       defaultValue: '*',
       description: 'Specify which installed versions should be hotlinked.'
     });
 
-    this._subspaceNamesParameter = this.defineStringListParameter({
+    this.#subspaceNamesParameter = this.defineStringListParameter({
       parameterLongName: '--subspace',
       argumentName: 'SUBSPACE_NAME',
       description: 'The name of the subspace to use for the hotlinked package.'
     });
   }
 
-  private _getSubspacesToBridgeAsync(): Set<Subspace> {
+  #getSubspacesToBridgeAsync(): Set<Subspace> {
     const subspaceToBridge: Set<Subspace> = new Set();
-    const subspaceNames: readonly string[] = this._subspaceNamesParameter.values;
+    const subspaceNames: readonly string[] = this.#subspaceNamesParameter.values;
 
     if (subspaceNames.length > 0) {
       for (const subspaceName of subspaceNames) {
@@ -79,8 +79,8 @@ export class BridgePackageAction extends BaseHotlinkPackageAction {
     linkedPackagePath: string,
     hotlinkManager: HotlinkManager
   ): Promise<void> {
-    const version: string = this._versionParameter.value;
-    const subspaces: Set<Subspace> = await this._getSubspacesToBridgeAsync();
+    const version: string = this.#versionParameter.value;
+    const subspaces: Set<Subspace> = await this.#getSubspacesToBridgeAsync();
     await Async.forEachAsync(
       subspaces,
       async (subspace) => {
diff --git a/libraries/rush-lib/src/cli/actions/ChangeAction.ts b/libraries/rush-lib/src/cli/actions/ChangeAction.ts
index fed5bb1f8f5..8830df2936f 100644
--- a/libraries/rush-lib/src/cli/actions/ChangeAction.ts
+++ b/libraries/rush-lib/src/cli/actions/ChangeAction.ts
@@ -36,20 +36,20 @@ const BULK_MESSAGE_LONG_NAME: string = '--message';
 const BULK_BUMP_TYPE_LONG_NAME: string = '--bump-type';
 
 export class ChangeAction extends BaseRushAction {
-  private readonly _git: Git;
-  private readonly _verifyParameter: CommandLineFlagParameter;
-  private readonly _verifyAllParameter: CommandLineFlagParameter;
-  private readonly _noFetchParameter: CommandLineFlagParameter;
-  private readonly _targetBranchParameter: CommandLineStringParameter;
-  private readonly _changeEmailParameter: CommandLineStringParameter;
-  private readonly _bulkChangeParameter: CommandLineFlagParameter;
-  private readonly _bulkChangeMessageParameter: CommandLineStringParameter;
-  private readonly _bulkChangeBumpTypeParameter: CommandLineChoiceParameter;
-  private readonly _overwriteFlagParameter: CommandLineFlagParameter;
-  private readonly _commitChangesFlagParameter: CommandLineFlagParameter;
-  private readonly _commitChangesMessageStringParameter: CommandLineStringParameter;
-
-  private _targetBranchName: string | undefined;
+  readonly #git: Git;
+  readonly #verifyParameter: CommandLineFlagParameter;
+  readonly #verifyAllParameter: CommandLineFlagParameter;
+  readonly #noFetchParameter: CommandLineFlagParameter;
+  readonly #targetBranchParameter: CommandLineStringParameter;
+  readonly #changeEmailParameter: CommandLineStringParameter;
+  readonly #bulkChangeParameter: CommandLineFlagParameter;
+  readonly #bulkChangeMessageParameter: CommandLineStringParameter;
+  readonly #bulkChangeBumpTypeParameter: CommandLineChoiceParameter;
+  readonly #overwriteFlagParameter: CommandLineFlagParameter;
+  readonly #commitChangesFlagParameter: CommandLineFlagParameter;
+  readonly #commitChangesMessageStringParameter: CommandLineStringParameter;
+
+  #targetBranchName: string | undefined;
 
   public constructor(parser: RushCommandLineParser) {
     const documentation: string = [
@@ -91,15 +91,15 @@ export class ChangeAction extends BaseRushAction {
       parser
     });
 
-    this._git = new Git(this.rushConfiguration);
+    this.#git = new Git(this.rushConfiguration);
 
-    this._verifyParameter = this.defineFlagParameter({
+    this.#verifyParameter = this.defineFlagParameter({
       parameterLongName: '--verify',
       parameterShortName: '-v',
       description: 'Verify the change file has been generated and that it is a valid JSON file'
     });
 
-    this._verifyAllParameter = this.defineFlagParameter({
+    this.#verifyAllParameter = this.defineFlagParameter({
       parameterLongName: '--verify-all',
       description:
         'Validate all change files in the repository, not just those added in the current branch. ' +
@@ -107,12 +107,12 @@ export class ChangeAction extends BaseRushAction {
         'in a lockstepped version policy. Requires the "strictChangefileValidation" experiment to be enabled.'
     });
 
-    this._noFetchParameter = this.defineFlagParameter({
+    this.#noFetchParameter = this.defineFlagParameter({
       parameterLongName: '--no-fetch',
       description: 'Skips fetching the baseline branch before running "git diff" to detect changes.'
     });
 
-    this._targetBranchParameter = this.defineStringParameter({
+    this.#targetBranchParameter = this.defineStringParameter({
       parameterLongName: '--target-branch',
       parameterShortName: '-b',
       argumentName: 'BRANCH',
@@ -122,26 +122,26 @@ export class ChangeAction extends BaseRushAction {
         'is compared against the "main" branch.'
     });
 
-    this._overwriteFlagParameter = this.defineFlagParameter({
+    this.#overwriteFlagParameter = this.defineFlagParameter({
       parameterLongName: '--overwrite',
       description:
         `If a changefile already exists, overwrite without prompting ` +
         `(or erroring in ${BULK_LONG_NAME} mode).`
     });
 
-    this._commitChangesFlagParameter = this.defineFlagParameter({
+    this.#commitChangesFlagParameter = this.defineFlagParameter({
       parameterLongName: '--commit',
       parameterShortName: '-c',
       description: `If this flag is specified generated changefiles will be commited automatically.`
     });
 
-    this._commitChangesMessageStringParameter = this.defineStringParameter({
+    this.#commitChangesMessageStringParameter = this.defineStringParameter({
       parameterLongName: '--commit-message',
       argumentName: 'COMMIT_MESSAGE',
       description: `If this parameter is specified generated changefiles will be commited automatically with the specified commit message.`
     });
 
-    this._changeEmailParameter = this.defineStringParameter({
+    this.#changeEmailParameter = this.defineStringParameter({
       parameterLongName: '--email',
       argumentName: 'EMAIL',
       description:
@@ -149,7 +149,7 @@ export class ChangeAction extends BaseRushAction {
         'will be detected or prompted for in interactive mode.'
     });
 
-    this._bulkChangeParameter = this.defineFlagParameter({
+    this.#bulkChangeParameter = this.defineFlagParameter({
       parameterLongName: BULK_LONG_NAME,
       description:
         'If this flag is specified, apply the same change message and bump type to all changed projects. ' +
@@ -157,39 +157,39 @@ export class ChangeAction extends BaseRushAction {
         `${BULK_LONG_NAME} parameter is specified`
     });
 
-    this._bulkChangeMessageParameter = this.defineStringParameter({
+    this.#bulkChangeMessageParameter = this.defineStringParameter({
       parameterLongName: BULK_MESSAGE_LONG_NAME,
       argumentName: 'MESSAGE',
       description: `The message to apply to all changed projects if the ${BULK_LONG_NAME} flag is provided.`
     });
 
-    this._bulkChangeBumpTypeParameter = this.defineChoiceParameter({
+    this.#bulkChangeBumpTypeParameter = this.defineChoiceParameter({
       parameterLongName: BULK_BUMP_TYPE_LONG_NAME,
-      alternatives: [...Object.keys(this._getBumpOptions())],
+      alternatives: [...Object.keys(this.#getBumpOptions())],
       description: `The bump type to apply to all changed projects if the ${BULK_LONG_NAME} flag is provided.`
     });
   }
 
   public async runAsync(): Promise<void> {
-    if (this._verifyAllParameter.value) {
+    if (this.#verifyAllParameter.value) {
       const incompatibleParameters: (
         | CommandLineFlagParameter
         | CommandLineStringParameter
         | CommandLineChoiceParameter
       )[] = [
-        this._verifyParameter,
-        this._bulkChangeParameter,
-        this._bulkChangeMessageParameter,
-        this._bulkChangeBumpTypeParameter,
-        this._overwriteFlagParameter,
-        this._commitChangesFlagParameter
+        this.#verifyParameter,
+        this.#bulkChangeParameter,
+        this.#bulkChangeMessageParameter,
+        this.#bulkChangeBumpTypeParameter,
+        this.#overwriteFlagParameter,
+        this.#commitChangesFlagParameter
       ];
       const errors: string[] = incompatibleParameters
         .filter((parameter) => parameter.value)
         .map(
           (parameter) =>
             `The ${parameter.longName} parameter cannot be provided with the ` +
-            `${this._verifyAllParameter.longName} parameter`
+            `${this.#verifyAllParameter.longName} parameter`
         );
       if (errors.length > 0) {
         errors.forEach((error) => {
@@ -198,30 +198,30 @@ export class ChangeAction extends BaseRushAction {
         throw new AlreadyReportedError();
       }
 
-      await this._validateAllChangeFilesAsync();
+      await this.#validateAllChangeFilesAsync();
       return;
     }
 
-    const targetBranch: string = await this._getTargetBranchAsync();
+    const targetBranch: string = await this.#getTargetBranchAsync();
     this.terminal.writeLine(`The target branch is ${targetBranch}`);
 
-    if (this._verifyParameter.value) {
+    if (this.#verifyParameter.value) {
       const incompatibleParameters: (
         | CommandLineFlagParameter
         | CommandLineStringParameter
         | CommandLineChoiceParameter
       )[] = [
-        this._bulkChangeParameter,
-        this._bulkChangeMessageParameter,
-        this._bulkChangeBumpTypeParameter,
-        this._overwriteFlagParameter,
-        this._commitChangesFlagParameter
+        this.#bulkChangeParameter,
+        this.#bulkChangeMessageParameter,
+        this.#bulkChangeBumpTypeParameter,
+        this.#overwriteFlagParameter,
+        this.#commitChangesFlagParameter
       ];
       const errors: string[] = incompatibleParameters
         .map((parameter) => {
           return parameter.value
             ? `The ${parameter.longName} parameter cannot be provided with the ` +
-                `${this._verifyParameter.longName} parameter`
+                `${this.#verifyParameter.longName} parameter`
             : '';
         })
         .filter((error) => error !== '');
@@ -232,51 +232,51 @@ export class ChangeAction extends BaseRushAction {
         throw new AlreadyReportedError();
       }
 
-      await this._verifyAsync();
+      await this.#verifyAsync();
       return;
     }
 
-    const sortedProjectList: string[] = (await this._getChangedProjectNamesAsync()).sort();
+    const sortedProjectList: string[] = (await this.#getChangedProjectNamesAsync()).sort();
     if (sortedProjectList.length === 0) {
-      this._logNoChangeFileRequired();
-      await this._warnUnstagedChangesAsync();
+      this.#logNoChangeFileRequired();
+      await this.#warnUnstagedChangesAsync();
       return;
     }
 
-    await this._warnUnstagedChangesAsync();
+    await this.#warnUnstagedChangesAsync();
 
     let changeFileData: Map<string, IChangeFile> = new Map<string, IChangeFile>();
     let interactiveMode: boolean = false;
-    if (this._bulkChangeParameter.value) {
+    if (this.#bulkChangeParameter.value) {
       if (
-        !this._bulkChangeBumpTypeParameter.value ||
-        (!this._bulkChangeMessageParameter.value &&
-          this._bulkChangeBumpTypeParameter.value !== ChangeType[ChangeType.none])
+        !this.#bulkChangeBumpTypeParameter.value ||
+        (!this.#bulkChangeMessageParameter.value &&
+          this.#bulkChangeBumpTypeParameter.value !== ChangeType[ChangeType.none])
       ) {
         throw new Error(
-          `The ${this._bulkChangeBumpTypeParameter.longName} and ${this._bulkChangeMessageParameter.longName} ` +
-            `parameters must provided if the ${this._bulkChangeParameter.longName} flag is provided. If the value ` +
+          `The ${this.#bulkChangeBumpTypeParameter.longName} and ${this.#bulkChangeMessageParameter.longName} ` +
+            `parameters must provided if the ${this.#bulkChangeParameter.longName} flag is provided. If the value ` +
             `"${ChangeType[ChangeType.none]}" is provided to the ${
-              this._bulkChangeBumpTypeParameter.longName
+              this.#bulkChangeBumpTypeParameter.longName
             } ` +
-            `parameter, the ${this._bulkChangeMessageParameter.longName} parameter may be omitted.`
+            `parameter, the ${this.#bulkChangeMessageParameter.longName} parameter may be omitted.`
         );
       }
 
-      const email: string | undefined = this._changeEmailParameter.value || this._detectEmail();
+      const email: string | undefined = this.#changeEmailParameter.value || this.#detectEmail();
       if (!email) {
         throw new Error(
           "Unable to detect Git email and an email address wasn't provided using the " +
-            `${this._changeEmailParameter.longName} parameter.`
+            `${this.#changeEmailParameter.longName} parameter.`
         );
       }
 
       const errors: string[] = [];
 
-      const comment: string = this._bulkChangeMessageParameter.value || '';
-      const changeType: string = this._bulkChangeBumpTypeParameter.value;
+      const comment: string = this.#bulkChangeMessageParameter.value || '';
+      const changeType: string = this.#bulkChangeBumpTypeParameter.value;
       for (const packageName of sortedProjectList) {
-        const allowedBumpTypes: string[] = Object.keys(this._getBumpOptions(packageName));
+        const allowedBumpTypes: string[] = Object.keys(this.#getBumpOptions(packageName));
         let projectChangeType: string = changeType;
         if (allowedBumpTypes.length === 0) {
           projectChangeType = ChangeType[ChangeType.none];
@@ -307,27 +307,27 @@ export class ChangeAction extends BaseRushAction {
 
         throw new AlreadyReportedError();
       }
-    } else if (this._bulkChangeBumpTypeParameter.value || this._bulkChangeMessageParameter.value) {
+    } else if (this.#bulkChangeBumpTypeParameter.value || this.#bulkChangeMessageParameter.value) {
       throw new Error(
-        `The ${this._bulkChangeParameter.longName} flag must be provided with the ` +
-          `${this._bulkChangeBumpTypeParameter.longName} and ${this._bulkChangeMessageParameter.longName} parameters.`
+        `The ${this.#bulkChangeParameter.longName} flag must be provided with the ` +
+          `${this.#bulkChangeBumpTypeParameter.longName} and ${this.#bulkChangeMessageParameter.longName} parameters.`
       );
     } else {
       interactiveMode = true;
 
       const existingChangeComments: Map<string, string[]> = ChangeFiles.getChangeComments(
         this.terminal,
-        await this._getChangeFilesSinceBaseBranchAsync()
+        await this.#getChangeFilesSinceBaseBranchAsync()
       );
-      changeFileData = await this._promptForChangeFileDataAsync(
+      changeFileData = await this.#promptForChangeFileDataAsync(
         sortedProjectList,
         existingChangeComments
       );
 
-      if (this._isEmailRequired(changeFileData)) {
-        const email: string = this._changeEmailParameter.value
-          ? this._changeEmailParameter.value
-          : await this._detectOrAskForEmailAsync();
+      if (this.#isEmailRequired(changeFileData)) {
+        const email: string = this.#changeEmailParameter.value
+          ? this.#changeEmailParameter.value
+          : await this.#detectOrAskForEmailAsync();
         changeFileData.forEach((changeFile: IChangeFile) => {
           changeFile.email = this.rushConfiguration.getProjectByName(changeFile.packageName)?.versionPolicy
             ?.includeEmailInChangeFile
@@ -338,19 +338,19 @@ export class ChangeAction extends BaseRushAction {
     }
     let changefiles: string[];
     try {
-      changefiles = await this._writeChangeFilesAsync(
+      changefiles = await this.#writeChangeFilesAsync(
         changeFileData,
-        this._overwriteFlagParameter.value,
+        this.#overwriteFlagParameter.value,
         interactiveMode
       );
     } catch (error) {
       throw new Error(`There was an error creating a change file: ${(error as Error).toString()}`);
     }
-    if (this._commitChangesFlagParameter.value || this._commitChangesMessageStringParameter.value) {
+    if (this.#commitChangesFlagParameter.value || this.#commitChangesMessageStringParameter.value) {
       if (changefiles && changefiles.length !== 0) {
-        await this._git.stageAndCommitGitChangesAsync(
+        await this.#git.stageAndCommitGitChangesAsync(
           changefiles,
-          this._commitChangesMessageStringParameter.value ||
+          this.#commitChangesMessageStringParameter.value ||
             this.rushConfiguration.gitChangefilesCommitMessage ||
             'Rush change',
           this.terminal
@@ -361,7 +361,7 @@ export class ChangeAction extends BaseRushAction {
     }
   }
 
-  private _generateHostMap(): Map<RushConfigurationProject, string> {
+  #generateHostMap(): Map<RushConfigurationProject, string> {
     const hostMap: Map<RushConfigurationProject, string> = new Map();
     for (const project of this.rushConfiguration.projects) {
       let hostProjectName: string = project.packageName;
@@ -376,8 +376,8 @@ export class ChangeAction extends BaseRushAction {
     return hostMap;
   }
 
-  private async _verifyAsync(): Promise<void> {
-    const changedProjectNames: string[] = await this._getChangedProjectNamesAsync();
+  async #verifyAsync(): Promise<void> {
+    const changedProjectNames: string[] = await this.#getChangedProjectNamesAsync();
     const strictValidation: boolean | undefined =
       this.rushConfiguration.experimentsConfiguration.configuration.strictChangefileValidation;
 
@@ -388,12 +388,12 @@ export class ChangeAction extends BaseRushAction {
     if (strictValidation) {
       filesToValidate = await changeFilesInstance.getAllChangeFilesAsync();
     } else {
-      filesToValidate = await this._getChangeFilesSinceBaseBranchAsync();
+      filesToValidate = await this.#getChangeFilesSinceBaseBranchAsync();
     }
 
     if (changedProjectNames.length > 0 || filesToValidate.length > 0) {
       const deletedProjectNames: Set<string> | undefined = strictValidation
-        ? await this._getDeletedProjectNamesAsync()
+        ? await this.#getDeletedProjectNamesAsync()
         : undefined;
 
       await changeFilesInstance.validateAsync({
@@ -403,26 +403,26 @@ export class ChangeAction extends BaseRushAction {
         deletedProjectNames
       });
     } else {
-      this._logNoChangeFileRequired();
+      this.#logNoChangeFileRequired();
     }
   }
 
-  private async _getTargetBranchAsync(): Promise<string> {
-    if (!this._targetBranchName) {
-      this._targetBranchName =
-        this._targetBranchParameter.value || (await this._git.getRemoteDefaultBranchAsync());
+  async #getTargetBranchAsync(): Promise<string> {
+    if (!this.#targetBranchName) {
+      this.#targetBranchName =
+        this.#targetBranchParameter.value || (await this.#git.getRemoteDefaultBranchAsync());
     }
 
-    return this._targetBranchName;
+    return this.#targetBranchName;
   }
 
-  private async _getChangedProjectNamesAsync(): Promise<string[]> {
+  async #getChangedProjectNamesAsync(): Promise<string[]> {
     const projectChangeAnalyzer: ProjectChangeAnalyzer = new ProjectChangeAnalyzer(this.rushConfiguration);
     const changedProjects: Set<RushConfigurationProject> =
       await projectChangeAnalyzer.getChangedProjectsAsync({
-        targetBranchName: await this._getTargetBranchAsync(),
+        targetBranchName: await this.#getTargetBranchAsync(),
         terminal: this.terminal,
-        shouldFetch: !this._noFetchParameter.value,
+        shouldFetch: !this.#noFetchParameter.value,
         // Lockfile evaluation will expand the set of projects that request change files
         // Not enabling, since this would be a breaking change
         includeExternalDependencies: false,
@@ -431,7 +431,7 @@ export class ChangeAction extends BaseRushAction {
         // Exclude version-only changes to prevent 'rush version --bump' from triggering 'rush change --verify'
         excludeVersionOnlyChanges: true
       });
-    const projectHostMap: Map<RushConfigurationProject, string> = this._generateHostMap();
+    const projectHostMap: Map<RushConfigurationProject, string> = this.#generateHostMap();
 
     const changedProjectNames: Set<string> = new Set<string>();
     for (const changedProject of changedProjects) {
@@ -446,17 +446,17 @@ export class ChangeAction extends BaseRushAction {
     return Array.from(changedProjectNames);
   }
 
-  private async _validateAllChangeFilesAsync(): Promise<void> {
+  async #validateAllChangeFilesAsync(): Promise<void> {
     if (!this.rushConfiguration.experimentsConfiguration.configuration.strictChangefileValidation) {
       throw new Error(
-        `The ${this._verifyAllParameter.longName} parameter requires the ` +
+        `The ${this.#verifyAllParameter.longName} parameter requires the ` +
           '"strictChangefileValidation" experiment to be enabled.'
       );
     }
 
     const changeFiles: ChangeFiles = new ChangeFiles(this.rushConfiguration);
     const allChangeFiles: string[] = await changeFiles.getAllChangeFilesAsync();
-    const deletedProjectNames: Set<string> = await this._getDeletedProjectNamesAsync();
+    const deletedProjectNames: Set<string> = await this.#getDeletedProjectNamesAsync();
     await changeFiles.validateAsync({
       terminal: this.terminal,
       filesToValidate: allChangeFiles,
@@ -469,15 +469,15 @@ export class ChangeAction extends BaseRushAction {
    * Compares the current rush.json project list against the target branch to find
    * projects that were removed.
    */
-  private async _getDeletedProjectNamesAsync(): Promise<Set<string>> {
+  async #getDeletedProjectNamesAsync(): Promise<Set<string>> {
     const repoRoot: string = getRepoRoot(this.rushConfiguration.rushJsonFolder);
-    const targetBranch: string = await this._getTargetBranchAsync();
-    const mergeBase: string = await this._git.getMergeBaseAsync(targetBranch, this.terminal);
+    const targetBranch: string = await this.#getTargetBranchAsync();
+    const mergeBase: string = await this.#git.getMergeBaseAsync(targetBranch, this.terminal);
 
     let oldRushJsonContent: string;
     try {
       const rushJsonRelativePath: string = path.relative(repoRoot, this.rushConfiguration.rushJsonFile);
-      oldRushJsonContent = await this._git.getBlobContentAsync({
+      oldRushJsonContent = await this.#git.getBlobContentAsync({
         blobSpec: `${mergeBase}:${rushJsonRelativePath}`,
         repositoryRoot: repoRoot
       });
@@ -500,11 +500,11 @@ export class ChangeAction extends BaseRushAction {
     return deletedProjectNames;
   }
 
-  private async _getChangeFilesSinceBaseBranchAsync(): Promise<string[]> {
+  async #getChangeFilesSinceBaseBranchAsync(): Promise<string[]> {
     const repoRoot: string = getRepoRoot(this.rushConfiguration.rushJsonFolder);
     const relativeChangesFolder: string = path.relative(repoRoot, this.rushConfiguration.changesFolder);
-    const targetBranch: string = await this._getTargetBranchAsync();
-    const changedFiles: string[] = await this._git.getChangedFilesAsync(
+    const targetBranch: string = await this.#getTargetBranchAsync();
+    const changedFiles: string[] = await this.#git.getChangedFilesAsync(
       targetBranch,
       this.terminal,
       true,
@@ -522,14 +522,14 @@ export class ChangeAction extends BaseRushAction {
   /**
    * The main loop which prompts the user for information on changed projects.
    */
-  private async _promptForChangeFileDataAsync(
+  async #promptForChangeFileDataAsync(
     sortedProjectList: string[],
     existingChangeComments: Map<string, string[]>
   ): Promise<Map<string, IChangeFile>> {
     const changedFileData: Map<string, IChangeFile> = new Map<string, IChangeFile>();
 
     for (const projectName of sortedProjectList) {
-      const changeInfo: IChangeInfo | undefined = await this._askQuestionsAsync(
+      const changeInfo: IChangeInfo | undefined = await this.#askQuestionsAsync(
         projectName,
         existingChangeComments
       );
@@ -555,7 +555,7 @@ export class ChangeAction extends BaseRushAction {
   /**
    * Asks all questions which are needed to generate changelist for a project.
    */
-  private async _askQuestionsAsync(
+  async #askQuestionsAsync(
     packageName: string,
     existingChangeComments: Map<string, string[]>
   ): Promise<IChangeInfo | undefined> {
@@ -585,17 +585,17 @@ export class ChangeAction extends BaseRushAction {
       if (appendComment === 'skip') {
         return undefined;
       } else {
-        return await this._promptForCommentsAsync(packageName);
+        return await this.#promptForCommentsAsync(packageName);
       }
     } else {
-      return await this._promptForCommentsAsync(packageName);
+      return await this.#promptForCommentsAsync(packageName);
     }
   }
 
-  private async _promptForCommentsAsync(
+  async #promptForCommentsAsync(
     packageName: string
   ): Promise<IChangeInfo | undefined> {
-    const bumpOptions: { [type: string]: string } = this._getBumpOptions(packageName);
+    const bumpOptions: { [type: string]: string } = this.#getBumpOptions(packageName);
     const { default: input } = await import('@inquirer/input');
     const comment: string = await input({ message: `Describe changes, or ENTER if no changes:` });
 
@@ -626,7 +626,7 @@ export class ChangeAction extends BaseRushAction {
     }
   }
 
-  private _getBumpOptions(packageName?: string): { [type: string]: string } {
+  #getBumpOptions(packageName?: string): { [type: string]: string } {
     let bumpOptions: { [type: string]: string } =
       this.rushConfiguration && this.rushConfiguration.hotfixChangeEnabled
         ? {
@@ -667,7 +667,7 @@ export class ChangeAction extends BaseRushAction {
     return bumpOptions;
   }
 
-  private _isEmailRequired(changeFileData: Map<string, IChangeFile>): boolean {
+  #isEmailRequired(changeFileData: Map<string, IChangeFile>): boolean {
     return [...changeFileData.values()].some(
       (changeFile) =>
         !!this.rushConfiguration.getProjectByName(changeFile.packageName)?.versionPolicy
@@ -679,14 +679,14 @@ export class ChangeAction extends BaseRushAction {
    * Will determine a user's email by first detecting it from their Git config,
    * or will ask for it if it is not found or the Git config is wrong.
    */
-  private async _detectOrAskForEmailAsync(): Promise<string> {
+  async #detectOrAskForEmailAsync(): Promise<string> {
     return (
-      (await this._detectAndConfirmEmailAsync()) ||
-      (await this._promptForEmailAsync())
+      (await this.#detectAndConfirmEmailAsync()) ||
+      (await this.#promptForEmailAsync())
     );
   }
 
-  private _detectEmail(): string | undefined {
+  #detectEmail(): string | undefined {
     try {
       return child_process
         .execSync('git config user.email')
@@ -702,8 +702,8 @@ export class ChangeAction extends BaseRushAction {
    * Detects the user's email address from their Git configuration, prompts the user to approve the
    * detected email. It returns undefined if it cannot be detected.
    */
-  private async _detectAndConfirmEmailAsync(): Promise<string | undefined> {
-    const email: string | undefined = this._detectEmail();
+  async #detectAndConfirmEmailAsync(): Promise<string | undefined> {
+    const email: string | undefined = this.#detectEmail();
 
     if (email) {
       const { default: confirm } = await import('@inquirer/confirm');
@@ -720,7 +720,7 @@ export class ChangeAction extends BaseRushAction {
   /**
    * Asks the user for their email address
    */
-  private async _promptForEmailAsync(): Promise<string> {
+  async #promptForEmailAsync(): Promise<string> {
     const { default: input } = await import('@inquirer/input');
     return await input({
       message: 'What is your email address?',
@@ -730,9 +730,9 @@ export class ChangeAction extends BaseRushAction {
     });
   }
 
-  private async _warnUnstagedChangesAsync(): Promise<void> {
+  async #warnUnstagedChangesAsync(): Promise<void> {
     try {
-      const hasUnstagedChanges: boolean = await this._git.hasUnstagedChangesAsync();
+      const hasUnstagedChanges: boolean = await this.#git.hasUnstagedChangesAsync();
       if (hasUnstagedChanges) {
         this.terminal.writeLine(
           '\n' +
@@ -750,14 +750,14 @@ export class ChangeAction extends BaseRushAction {
   /**
    * Writes change files to the common/changes folder. Will prompt for overwrite if file already exists.
    */
-  private async _writeChangeFilesAsync(
+  async #writeChangeFilesAsync(
     changeFileData: Map<string, IChangeFile>,
     overwrite: boolean,
     interactiveMode: boolean
   ): Promise<string[]> {
     const writtenFiles: string[] = [];
     await changeFileData.forEach(async (changeFile: IChangeFile) => {
-      const writtenFile: string | undefined = await this._writeChangeFileAsync(
+      const writtenFile: string | undefined = await this.#writeChangeFileAsync(
         changeFile,
         overwrite,
         interactiveMode
@@ -769,7 +769,7 @@ export class ChangeAction extends BaseRushAction {
     return writtenFiles;
   }
 
-  private async _writeChangeFileAsync(
+  async #writeChangeFileAsync(
     changeFileData: IChangeFile,
     overwrite: boolean,
     interactiveMode: boolean
@@ -782,19 +782,19 @@ export class ChangeAction extends BaseRushAction {
     const shouldWrite: boolean =
       !fileExists ||
       overwrite ||
-      (interactiveMode ? await this._promptForOverwriteAsync(filePath) : false);
+      (interactiveMode ? await this.#promptForOverwriteAsync(filePath) : false);
 
     if (!interactiveMode && fileExists && !overwrite) {
       throw new Error(`Changefile ${filePath} already exists`);
     }
 
     if (shouldWrite) {
-      this._writeFile(filePath, output, shouldWrite && fileExists);
+      this.#writeFile(filePath, output, shouldWrite && fileExists);
       return filePath;
     }
   }
 
-  private async _promptForOverwriteAsync(
+  async #promptForOverwriteAsync(
     filePath: string
   ): Promise<boolean> {
     const { default: confirm } = await import('@inquirer/confirm');
@@ -813,7 +813,7 @@ export class ChangeAction extends BaseRushAction {
   /**
    * Writes a file to disk, ensuring the directory structure up to that point exists
    */
-  private _writeFile(fileName: string, output: string, isOverwrite: boolean): void {
+  #writeFile(fileName: string, output: string, isOverwrite: boolean): void {
     FileSystem.writeFile(fileName, output, { ensureFolderExists: true });
     if (isOverwrite) {
       this.terminal.writeLine(`Overwrote file: ${fileName}`);
@@ -822,7 +822,7 @@ export class ChangeAction extends BaseRushAction {
     }
   }
 
-  private _logNoChangeFileRequired(): void {
+  #logNoChangeFileRequired(): void {
     this.terminal.writeLine('No changes were detected to relevant packages on this branch. Nothing to do.');
   }
 }
diff --git a/libraries/rush-lib/src/cli/actions/CheckAction.ts b/libraries/rush-lib/src/cli/actions/CheckAction.ts
index fcf752b0657..5bc423c5c19 100644
--- a/libraries/rush-lib/src/cli/actions/CheckAction.ts
+++ b/libraries/rush-lib/src/cli/actions/CheckAction.ts
@@ -10,10 +10,10 @@ import { VersionMismatchFinder } from '../../logic/versionMismatch/VersionMismat
 import { getVariantAsync, VARIANT_PARAMETER } from '../../api/Variants';
 
 export class CheckAction extends BaseRushAction {
-  private readonly _jsonFlag: CommandLineFlagParameter;
-  private readonly _verboseFlag: CommandLineFlagParameter;
-  private readonly _subspaceParameter: CommandLineStringParameter | undefined;
-  private readonly _variantParameter: CommandLineStringParameter;
+  readonly #jsonFlag: CommandLineFlagParameter;
+  readonly #verboseFlag: CommandLineFlagParameter;
+  readonly #subspaceParameter: CommandLineStringParameter | undefined;
+  readonly #variantParameter: CommandLineStringParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -28,17 +28,17 @@ export class CheckAction extends BaseRushAction {
       parser
     });
 
-    this._jsonFlag = this.defineFlagParameter({
+    this.#jsonFlag = this.defineFlagParameter({
       parameterLongName: '--json',
       description: 'If this flag is specified, output will be in JSON format.'
     });
-    this._verboseFlag = this.defineFlagParameter({
+    this.#verboseFlag = this.defineFlagParameter({
       parameterLongName: '--verbose',
       description:
         'If this flag is specified, long lists of package names will not be truncated. ' +
-        `This has no effect if the ${this._jsonFlag.longName} flag is also specified.`
+        `This has no effect if the ${this.#jsonFlag.longName} flag is also specified.`
     });
-    this._subspaceParameter = this.defineStringParameter({
+    this.#subspaceParameter = this.defineStringParameter({
       parameterLongName: '--subspace',
       argumentName: 'SUBSPACE_NAME',
       description:
@@ -46,11 +46,11 @@ export class CheckAction extends BaseRushAction {
         'consistent only within that subspace (ignoring other subspaces). This parameter is required when ' +
         'the "subspacesEnabled" setting is set to true in subspaces.json.'
     });
-    this._variantParameter = this.defineStringParameter(VARIANT_PARAMETER);
+    this.#variantParameter = this.defineStringParameter(VARIANT_PARAMETER);
   }
 
   protected async runAsync(): Promise<void> {
-    if (this.rushConfiguration.subspacesFeatureEnabled && !this._subspaceParameter) {
+    if (this.rushConfiguration.subspacesFeatureEnabled && !this.#subspaceParameter) {
       throw new Error(
         `The --subspace parameter must be specified with "rush check" when subspaces is enabled.`
       );
@@ -59,7 +59,7 @@ export class CheckAction extends BaseRushAction {
     const currentlyInstalledVariant: string | undefined =
       await this.rushConfiguration.getCurrentlyInstalledVariantAsync();
     const variant: string | undefined = await getVariantAsync(
-      this._variantParameter,
+      this.#variantParameter,
       this.rushConfiguration,
       true
     );
@@ -67,17 +67,17 @@ export class CheckAction extends BaseRushAction {
       this.terminal.writeWarningLine(
         Colorize.yellow(
           `Variant '${currentlyInstalledVariant}' has been installed, but 'rush check' is currently checking the default variant. ` +
-            `Use 'rush ${this.actionName} ${this._variantParameter.longName} '${currentlyInstalledVariant}' to check the current installation.`
+            `Use 'rush ${this.actionName} ${this.#variantParameter.longName} '${currentlyInstalledVariant}' to check the current installation.`
         )
       );
     }
 
     VersionMismatchFinder.rushCheck(this.rushConfiguration, this.terminal, {
       variant,
-      printAsJson: this._jsonFlag.value,
-      truncateLongPackageNameLists: !this._verboseFlag.value,
-      subspace: this._subspaceParameter?.value
-        ? this.rushConfiguration.getSubspace(this._subspaceParameter.value)
+      printAsJson: this.#jsonFlag.value,
+      truncateLongPackageNameLists: !this.#verboseFlag.value,
+      subspace: this.#subspaceParameter?.value
+        ? this.rushConfiguration.getSubspace(this.#subspaceParameter.value)
         : this.rushConfiguration.defaultSubspace
     });
   }
diff --git a/libraries/rush-lib/src/cli/actions/DeployAction.ts b/libraries/rush-lib/src/cli/actions/DeployAction.ts
index ebbf57c7eeb..62c9c33da88 100644
--- a/libraries/rush-lib/src/cli/actions/DeployAction.ts
+++ b/libraries/rush-lib/src/cli/actions/DeployAction.ts
@@ -21,13 +21,13 @@ import type {
 import type { RushConfigurationProject } from '../../api/RushConfigurationProject';
 
 export class DeployAction extends BaseRushAction {
-  private readonly _logger: ILogger;
-  private readonly _scenario: CommandLineStringParameter;
-  private readonly _project: CommandLineStringParameter;
-  private readonly _overwrite: CommandLineFlagParameter;
-  private readonly _targetFolder: CommandLineStringParameter;
-  private readonly _createArchivePath: CommandLineStringParameter;
-  private readonly _createArchiveOnly: CommandLineFlagParameter;
+  readonly #logger: ILogger;
+  readonly #scenario: CommandLineStringParameter;
+  readonly #project: CommandLineStringParameter;
+  readonly #overwrite: CommandLineFlagParameter;
+  readonly #targetFolder: CommandLineStringParameter;
+  readonly #createArchivePath: CommandLineStringParameter;
+  readonly #createArchiveOnly: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -47,9 +47,9 @@ export class DeployAction extends BaseRushAction {
       safeForSimultaneousRushProcesses: true
     });
 
-    this._logger = this.rushSession.getLogger('deploy');
+    this.#logger = this.rushSession.getLogger('deploy');
 
-    this._project = this.defineStringParameter({
+    this.#project = this.defineStringParameter({
       parameterLongName: '--project',
       parameterShortName: '-p',
       argumentName: 'PROJECT_NAME',
@@ -58,7 +58,7 @@ export class DeployAction extends BaseRushAction {
         ' "deploymentProjectNames" setting in the deployment config file.'
     });
 
-    this._scenario = this.defineStringParameter({
+    this.#scenario = this.defineStringParameter({
       parameterLongName: '--scenario',
       parameterShortName: '-s',
       argumentName: 'SCENARIO_NAME',
@@ -68,14 +68,14 @@ export class DeployAction extends BaseRushAction {
         ' For example, if SCENARIO_NAME is "web", then the config file would be "common/config/rush/deploy-web.json".'
     });
 
-    this._overwrite = this.defineFlagParameter({
+    this.#overwrite = this.defineFlagParameter({
       parameterLongName: '--overwrite',
       description:
         'By default, deployment will fail if the target folder is not empty.  SPECIFYING THIS FLAG' +
         ' WILL RECURSIVELY DELETE EXISTING CONTENTS OF THE TARGET FOLDER.'
     });
 
-    this._targetFolder = this.defineStringParameter({
+    this.#targetFolder = this.defineStringParameter({
       parameterLongName: '--target-folder',
       parameterShortName: '-t',
       argumentName: 'PATH',
@@ -86,7 +86,7 @@ export class DeployAction extends BaseRushAction {
         ' WARNING: USE CAUTION WHEN COMBINING WITH "--overwrite"'
     });
 
-    this._createArchivePath = this.defineStringParameter({
+    this.#createArchivePath = this.defineStringParameter({
       parameterLongName: '--create-archive',
       argumentName: 'ARCHIVE_PATH',
       description:
@@ -96,7 +96,7 @@ export class DeployAction extends BaseRushAction {
         ' to the target folder. Supported file extensions: .zip'
     });
 
-    this._createArchiveOnly = this.defineFlagParameter({
+    this.#createArchiveOnly = this.defineFlagParameter({
       parameterLongName: '--create-archive-only',
       description:
         'If specified, "rush deploy" will only create an archive containing the contents of the target folder.' +
@@ -105,19 +105,19 @@ export class DeployAction extends BaseRushAction {
   }
 
   protected async runAsync(): Promise<void> {
-    const scenarioName: string | undefined = this._scenario.value;
+    const scenarioName: string | undefined = this.#scenario.value;
     const { DeployScenarioConfiguration } = await import('../../logic/deploy/DeployScenarioConfiguration');
     const scenarioFilePath: string = DeployScenarioConfiguration.getConfigFilePath(
       scenarioName,
       this.rushConfiguration
     );
     const scenarioConfiguration: DeployScenarioConfiguration = DeployScenarioConfiguration.loadFromFile(
-      this._logger.terminal,
+      this.#logger.terminal,
       scenarioFilePath,
       this.rushConfiguration
     );
 
-    let mainProjectName: string | undefined = this._project.value;
+    let mainProjectName: string | undefined = this.#project.value;
     if (!mainProjectName) {
       if (scenarioConfiguration.json.deploymentProjectNames.length === 1) {
         // If there is only one project, then "--project" is optional
@@ -137,15 +137,15 @@ export class DeployAction extends BaseRushAction {
       }
     }
 
-    const targetRootFolder: string = this._targetFolder.value
-      ? path.resolve(this._targetFolder.value)
+    const targetRootFolder: string = this.#targetFolder.value
+      ? path.resolve(this.#targetFolder.value)
       : path.join(this.rushConfiguration.commonFolder, 'deploy');
 
-    const createArchiveFilePath: string | undefined = this._createArchivePath.value
-      ? path.resolve(targetRootFolder, this._createArchivePath.value)
+    const createArchiveFilePath: string | undefined = this.#createArchivePath.value
+      ? path.resolve(targetRootFolder, this.#createArchivePath.value)
       : undefined;
 
-    const createArchiveOnly: boolean = this._createArchiveOnly.value;
+    const createArchiveOnly: boolean = this.#createArchiveOnly.value;
 
     /**
      * Subspaces that will be involved in deploy process.
@@ -208,8 +208,8 @@ export class DeployAction extends BaseRushAction {
     );
     const deployManager: PackageExtractor = new PackageExtractor();
     await deployManager.extractAsync({
-      terminal: this._logger.terminal,
-      overwriteExisting: !!this._overwrite.value,
+      terminal: this.#logger.terminal,
+      overwriteExisting: !!this.#overwrite.value,
       includeDevDependencies: scenarioConfiguration.json.includeDevDependencies,
       includeNpmIgnoreFiles: scenarioConfiguration.json.includeNpmIgnoreFiles,
       folderToCopy: scenarioConfiguration.json.folderToCopy,
diff --git a/libraries/rush-lib/src/cli/actions/InitAction.ts b/libraries/rush-lib/src/cli/actions/InitAction.ts
index 7eeb7480312..45be135ac4b 100644
--- a/libraries/rush-lib/src/cli/actions/InitAction.ts
+++ b/libraries/rush-lib/src/cli/actions/InitAction.ts
@@ -18,12 +18,12 @@ import { assetsFolderPath } from '../../utilities/PathConstants';
 import { copyTemplateFileAsync } from '../../utilities/templateUtilities';
 
 export class InitAction extends BaseConfiglessRushAction {
-  private readonly _overwriteParameter: CommandLineFlagParameter;
-  private readonly _rushExampleParameter: CommandLineFlagParameter;
-  private readonly _experimentsParameter: CommandLineFlagParameter;
+  readonly #overwriteParameter: CommandLineFlagParameter;
+  readonly #rushExampleParameter: CommandLineFlagParameter;
+  readonly #experimentsParameter: CommandLineFlagParameter;
 
   // template section name --> whether it should be commented out
-  private _commentedBySectionName: Map<string, boolean> = new Map<string, boolean>();
+  #commentedBySectionName: Map<string, boolean> = new Map<string, boolean>();
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -35,21 +35,21 @@ export class InitAction extends BaseConfiglessRushAction {
       parser
     });
 
-    this._overwriteParameter = this.defineFlagParameter({
+    this.#overwriteParameter = this.defineFlagParameter({
       parameterLongName: '--overwrite-existing',
       description:
         'By default "rush init" will not overwrite existing config files.' +
         ' Specify this switch to override that. This can be useful when upgrading' +
         ' your repo to a newer release of Rush. WARNING: USE WITH CARE!'
     });
-    this._rushExampleParameter = this.defineFlagParameter({
+    this.#rushExampleParameter = this.defineFlagParameter({
       parameterLongName: '--rush-example-repo',
       description:
         'When copying the template config files, this uncomments fragments that are used' +
         ' by the "rush-example" GitHub repo, which is a sample monorepo that illustrates many Rush' +
         ' features. This option is primarily intended for maintaining that example.'
     });
-    this._experimentsParameter = this.defineFlagParameter({
+    this.#experimentsParameter = this.defineFlagParameter({
       parameterLongName: '--include-experiments',
       description:
         'Include features that may not be complete features, useful for demoing specific future features' +
@@ -60,17 +60,17 @@ export class InitAction extends BaseConfiglessRushAction {
   protected async runAsync(): Promise<void> {
     const initFolder: string = process.cwd();
 
-    if (!this._overwriteParameter.value) {
-      if (!this._validateFolderIsEmpty(initFolder)) {
+    if (!this.#overwriteParameter.value) {
+      if (!this.#validateFolderIsEmpty(initFolder)) {
         throw new AlreadyReportedError();
       }
     }
 
-    await this._copyTemplateFilesAsync(initFolder);
+    await this.#copyTemplateFilesAsync(initFolder);
   }
 
   // Check whether it's safe to run "rush init" in the current working directory.
-  private _validateFolderIsEmpty(initFolder: string): boolean {
+  #validateFolderIsEmpty(initFolder: string): boolean {
     if (this.rushConfiguration !== undefined) {
       // eslint-disable-next-line no-console
       console.error(
@@ -113,7 +113,7 @@ export class InitAction extends BaseConfiglessRushAction {
     return true;
   }
 
-  private async _copyTemplateFilesAsync(initFolder: string): Promise<void> {
+  async #copyTemplateFilesAsync(initFolder: string): Promise<void> {
     // The "[dot]" base name is used for hidden files to prevent various tools from interpreting them.
     // For example, "npm publish" will always exclude the filename ".gitignore"
     const templateFilePaths: string[] = [
@@ -143,7 +143,7 @@ export class InitAction extends BaseConfiglessRushAction {
 
     const experimentalTemplateFilePaths: string[] = ['common/config/rush/rush-alerts.json'];
 
-    if (this._experimentsParameter.value) {
+    if (this.#experimentsParameter.value) {
       templateFilePaths.push(...experimentalTemplateFilePaths);
     }
 
@@ -163,8 +163,8 @@ export class InitAction extends BaseConfiglessRushAction {
       await copyTemplateFileAsync(
         sourcePath,
         destinationPath,
-        this._overwriteParameter.value,
-        !this._rushExampleParameter.value
+        this.#overwriteParameter.value,
+        !this.#rushExampleParameter.value
       );
     }
   }
diff --git a/libraries/rush-lib/src/cli/actions/InitAutoinstallerAction.ts b/libraries/rush-lib/src/cli/actions/InitAutoinstallerAction.ts
index aebc4408103..1fea2fb46af 100644
--- a/libraries/rush-lib/src/cli/actions/InitAutoinstallerAction.ts
+++ b/libraries/rush-lib/src/cli/actions/InitAutoinstallerAction.ts
@@ -10,7 +10,7 @@ import type { RushCommandLineParser } from '../RushCommandLineParser';
 import { Autoinstaller } from '../../logic/Autoinstaller';
 
 export class InitAutoinstallerAction extends BaseRushAction {
-  private readonly _name: IRequiredCommandLineStringParameter;
+  readonly #name: IRequiredCommandLineStringParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -23,7 +23,7 @@ export class InitAutoinstallerAction extends BaseRushAction {
       parser
     });
 
-    this._name = this.defineStringParameter({
+    this.#name = this.defineStringParameter({
       parameterLongName: '--name',
       argumentName: 'AUTOINSTALLER_NAME',
       required: true,
@@ -33,7 +33,7 @@ export class InitAutoinstallerAction extends BaseRushAction {
   }
 
   protected async runAsync(): Promise<void> {
-    const autoinstallerName: string = this._name.value;
+    const autoinstallerName: string = this.#name.value;
 
     const autoinstaller: Autoinstaller = new Autoinstaller({
       autoinstallerName,
diff --git a/libraries/rush-lib/src/cli/actions/InitDeployAction.ts b/libraries/rush-lib/src/cli/actions/InitDeployAction.ts
index 6f7d996d7e7..3c8289be84e 100644
--- a/libraries/rush-lib/src/cli/actions/InitDeployAction.ts
+++ b/libraries/rush-lib/src/cli/actions/InitDeployAction.ts
@@ -18,8 +18,8 @@ import { RushConstants } from '../../logic/RushConstants';
 const CONFIG_TEMPLATE_PATH: string = `${assetsFolderPath}/rush-init-deploy/scenario-template.json`;
 
 export class InitDeployAction extends BaseRushAction {
-  private readonly _project: IRequiredCommandLineStringParameter;
-  private readonly _scenario: CommandLineStringParameter;
+  readonly #project: IRequiredCommandLineStringParameter;
+  readonly #scenario: CommandLineStringParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -32,7 +32,7 @@ export class InitDeployAction extends BaseRushAction {
       parser
     });
 
-    this._project = this.defineStringParameter({
+    this.#project = this.defineStringParameter({
       parameterLongName: '--project',
       parameterShortName: '-p',
       argumentName: 'PROJECT_NAME',
@@ -42,7 +42,7 @@ export class InitDeployAction extends BaseRushAction {
         ' It will be added to the "deploymentProjectNames" setting.'
     });
 
-    this._scenario = this.defineStringParameter({
+    this.#scenario = this.defineStringParameter({
       parameterLongName: '--scenario',
       parameterShortName: '-s',
       argumentName: 'SCENARIO',
@@ -55,7 +55,7 @@ export class InitDeployAction extends BaseRushAction {
 
   protected async runAsync(): Promise<void> {
     const scenarioFilePath: string = DeployScenarioConfiguration.getConfigFilePath(
-      this._scenario.value,
+      this.#scenario.value,
       this.rushConfiguration
     );
 
@@ -70,7 +70,7 @@ export class InitDeployAction extends BaseRushAction {
     // eslint-disable-next-line no-console
     console.log(Colorize.green('Creating scenario file: ') + scenarioFilePath);
 
-    const shortProjectName: string = this._project.value;
+    const shortProjectName: string = this.#project.value;
     const rushProject: RushConfigurationProject | undefined =
       this.rushConfiguration.findProjectByShorthandName(shortProjectName);
     if (!rushProject) {
diff --git a/libraries/rush-lib/src/cli/actions/InitSubspaceAction.ts b/libraries/rush-lib/src/cli/actions/InitSubspaceAction.ts
index 6659ae9ac81..b8dbeb019bd 100644
--- a/libraries/rush-lib/src/cli/actions/InitSubspaceAction.ts
+++ b/libraries/rush-lib/src/cli/actions/InitSubspaceAction.ts
@@ -12,7 +12,7 @@ import { type ISubspacesConfigurationJson, SubspacesConfiguration } from '../../
 import { copyTemplateFileAsync } from '../../utilities/templateUtilities';
 
 export class InitSubspaceAction extends BaseRushAction {
-  private readonly _subspaceNameParameter: IRequiredCommandLineStringParameter;
+  readonly #subspaceNameParameter: IRequiredCommandLineStringParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -23,7 +23,7 @@ export class InitSubspaceAction extends BaseRushAction {
       parser
     });
 
-    this._subspaceNameParameter = this.defineStringParameter({
+    this.#subspaceNameParameter = this.defineStringParameter({
       parameterLongName: '--name',
       parameterShortName: '-n',
       argumentName: 'SUBSPACE_NAME',
@@ -43,10 +43,10 @@ export class InitSubspaceAction extends BaseRushAction {
       .subspacesConfiguration as SubspacesConfiguration;
     // Verify this subspace name does not already exist
     const existingSubspaceNames: ReadonlySet<string> = subspacesConfiguration.subspaceNames;
-    const newSubspaceName: string = this._subspaceNameParameter.value;
+    const newSubspaceName: string = this.#subspaceNameParameter.value;
     if (existingSubspaceNames.has(newSubspaceName)) {
       throw new Error(
-        `The subspace name: ${this._subspaceNameParameter.value} already exists in the subspace.json file.`
+        `The subspace name: ${this.#subspaceNameParameter.value} already exists in the subspace.json file.`
       );
     }
     if (
diff --git a/libraries/rush-lib/src/cli/actions/InstallAction.ts b/libraries/rush-lib/src/cli/actions/InstallAction.ts
index ebc828c33b1..02869db9eea 100644
--- a/libraries/rush-lib/src/cli/actions/InstallAction.ts
+++ b/libraries/rush-lib/src/cli/actions/InstallAction.ts
@@ -12,8 +12,8 @@ import type { Subspace } from '../../api/Subspace';
 import { getVariantAsync } from '../../api/Variants';
 
 export class InstallAction extends BaseInstallAction {
-  private readonly _checkOnlyParameter: CommandLineFlagParameter;
-  private readonly _resolutionOnlyParameter: CommandLineFlagParameter | undefined;
+  readonly #checkOnlyParameter: CommandLineFlagParameter;
+  readonly #resolutionOnlyParameter: CommandLineFlagParameter | undefined;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -45,13 +45,13 @@ export class InstallAction extends BaseInstallAction {
       cwd: this.parser.cwd
     });
 
-    this._checkOnlyParameter = this.defineFlagParameter({
+    this.#checkOnlyParameter = this.defineFlagParameter({
       parameterLongName: '--check-only',
       description: `Only check the validity of the shrinkwrap file without performing an install.`
     });
 
     if (this.rushConfiguration?.isPnpm) {
-      this._resolutionOnlyParameter = this.defineFlagParameter({
+      this.#resolutionOnlyParameter = this.defineFlagParameter({
         parameterLongName: '--resolution-only',
         description: `Only perform dependency resolution, useful for ensuring peer dependendencies are up to date. Note that this flag is only supported when using the pnpm package manager.`
       });
@@ -88,8 +88,8 @@ export class InstallAction extends BaseInstallAction {
       selectedProjects,
       pnpmFilterArgumentValues:
         (await this._selectionParameters?.getPnpmFilterArgumentValuesAsync(this.terminal)) ?? [],
-      checkOnly: this._checkOnlyParameter.value,
-      resolutionOnly: this._resolutionOnlyParameter?.value,
+      checkOnly: this.#checkOnlyParameter.value,
+      resolutionOnly: this.#resolutionOnlyParameter?.value,
       beforeInstallAsync: (subspace: Subspace) =>
         this.rushSession.hooks.beforeInstall.promise(this, subspace, variant),
       afterInstallAsync: (subspace: Subspace) =>
diff --git a/libraries/rush-lib/src/cli/actions/LinkAction.ts b/libraries/rush-lib/src/cli/actions/LinkAction.ts
index eabf19c414c..52cca5068df 100644
--- a/libraries/rush-lib/src/cli/actions/LinkAction.ts
+++ b/libraries/rush-lib/src/cli/actions/LinkAction.ts
@@ -8,7 +8,7 @@ import type { BaseLinkManager } from '../../logic/base/BaseLinkManager';
 import { BaseRushAction } from './BaseRushAction';
 
 export class LinkAction extends BaseRushAction {
-  private readonly _force: CommandLineFlagParameter;
+  readonly #force: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -22,7 +22,7 @@ export class LinkAction extends BaseRushAction {
       parser
     });
 
-    this._force = this.defineFlagParameter({
+    this.#force = this.defineFlagParameter({
       parameterLongName: '--force',
       parameterShortName: '-f',
       description:
@@ -39,6 +39,6 @@ export class LinkAction extends BaseRushAction {
     const linkManager: BaseLinkManager = linkManagerFactoryModule.LinkManagerFactory.getLinkManager(
       this.rushConfiguration
     );
-    await linkManager.createSymlinksForProjectsAsync(this._force.value);
+    await linkManager.createSymlinksForProjectsAsync(this.#force.value);
   }
 }
diff --git a/libraries/rush-lib/src/cli/actions/LinkPackageAction.ts b/libraries/rush-lib/src/cli/actions/LinkPackageAction.ts
index 1d8352811f8..260ad109747 100644
--- a/libraries/rush-lib/src/cli/actions/LinkPackageAction.ts
+++ b/libraries/rush-lib/src/cli/actions/LinkPackageAction.ts
@@ -41,7 +41,7 @@ export class LinkPackageAction extends BaseHotlinkPackageAction {
     });
   }
 
-  private async _getProjectsToLinkAsync(): Promise<Set<RushConfigurationProject>> {
+  async #getProjectsToLinkAsync(): Promise<Set<RushConfigurationProject>> {
     const projectsToLink: Set<RushConfigurationProject> = new Set();
     const projectNames: readonly string[] = this._projectListParameter.values;
 
@@ -70,7 +70,7 @@ export class LinkPackageAction extends BaseHotlinkPackageAction {
     linkedPackagePath: string,
     hotlinkManager: HotlinkManager
   ): Promise<void> {
-    const projectsToLink: Set<RushConfigurationProject> = await this._getProjectsToLinkAsync();
+    const projectsToLink: Set<RushConfigurationProject> = await this.#getProjectsToLinkAsync();
     await Async.forEachAsync(
       projectsToLink,
       async (project) => {
diff --git a/libraries/rush-lib/src/cli/actions/ListAction.ts b/libraries/rush-lib/src/cli/actions/ListAction.ts
index 76583015535..124f7d7df29 100644
--- a/libraries/rush-lib/src/cli/actions/ListAction.ts
+++ b/libraries/rush-lib/src/cli/actions/ListAction.ts
@@ -56,12 +56,12 @@ export interface IJsonOutput {
 }
 
 export class ListAction extends BaseRushAction {
-  private readonly _version: CommandLineFlagParameter;
-  private readonly _path: CommandLineFlagParameter;
-  private readonly _fullPath: CommandLineFlagParameter;
-  private readonly _jsonFlag: CommandLineFlagParameter;
-  private readonly _detailedFlag: CommandLineFlagParameter;
-  private readonly _selectionParameters: SelectionParameterSet;
+  readonly #version: CommandLineFlagParameter;
+  readonly #path: CommandLineFlagParameter;
+  readonly #fullPath: CommandLineFlagParameter;
+  readonly #jsonFlag: CommandLineFlagParameter;
+  readonly #detailedFlag: CommandLineFlagParameter;
+  readonly #selectionParameters: SelectionParameterSet;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -75,7 +75,7 @@ export class ListAction extends BaseRushAction {
       safeForSimultaneousRushProcesses: true
     });
 
-    this._version = this.defineFlagParameter({
+    this.#version = this.defineFlagParameter({
       parameterLongName: '--version',
       parameterShortName: '-v',
       description:
@@ -83,7 +83,7 @@ export class ListAction extends BaseRushAction {
         'displayed in a column along with the package name.'
     });
 
-    this._path = this.defineFlagParameter({
+    this.#path = this.defineFlagParameter({
       parameterLongName: '--path',
       parameterShortName: '-p',
       description:
@@ -91,14 +91,14 @@ export class ListAction extends BaseRushAction {
         'displayed in a column along with the package name.'
     });
 
-    this._fullPath = this.defineFlagParameter({
+    this.#fullPath = this.defineFlagParameter({
       parameterLongName: '--full-path',
       description:
         'If this flag is specified, the project full path will ' +
         'be displayed in a column along with the package name.'
     });
 
-    this._detailedFlag = this.defineFlagParameter({
+    this.#detailedFlag = this.defineFlagParameter({
       parameterLongName: '--detailed',
       description:
         'For the non --json view, if this flag is specified, ' +
@@ -107,12 +107,12 @@ export class ListAction extends BaseRushAction {
         'shouldPublish, reviewPolicy, and tags fields.'
     });
 
-    this._jsonFlag = this.defineFlagParameter({
+    this.#jsonFlag = this.defineFlagParameter({
       parameterLongName: '--json',
       description: 'If this flag is specified, output will be in JSON format.'
     });
 
-    this._selectionParameters = new SelectionParameterSet(this.rushConfiguration, this, {
+    this.#selectionParameters = new SelectionParameterSet(this.rushConfiguration, this, {
       gitOptions: {
         // Include lockfile processing since this expands the selection, and we need to select
         // at least the same projects selected with the same query to "rush build"
@@ -128,22 +128,22 @@ export class ListAction extends BaseRushAction {
   protected async runAsync(): Promise<void> {
     const terminal: Terminal = new Terminal(new ConsoleTerminalProvider());
     const selection: Set<RushConfigurationProject> =
-      await this._selectionParameters.getSelectedProjectsAsync(terminal);
+      await this.#selectionParameters.getSelectedProjectsAsync(terminal);
     Sort.sortSetBy(selection, (x: RushConfigurationProject) => x.packageName);
-    if (this._jsonFlag.value && this._detailedFlag.value) {
+    if (this.#jsonFlag.value && this.#detailedFlag.value) {
       throw new Error(`The parameters "--json" and "--detailed" cannot be used together.`);
     }
 
-    if (this._jsonFlag.value) {
-      this._printJson(selection);
-    } else if (this._version.value || this._path.value || this._fullPath.value || this._detailedFlag.value) {
-      await this._printListTableAsync(selection);
+    if (this.#jsonFlag.value) {
+      this.#printJson(selection);
+    } else if (this.#version.value || this.#path.value || this.#fullPath.value || this.#detailedFlag.value) {
+      await this.#printListTableAsync(selection);
     } else {
-      this._printList(selection);
+      this.#printList(selection);
     }
   }
 
-  private _printJson(selection: Set<RushConfigurationProject>): void {
+  #printJson(selection: Set<RushConfigurationProject>): void {
     const projects: IJsonEntry[] = Array.from(selection, (config: RushConfigurationProject): IJsonEntry => {
       let reviewCategory: undefined | string;
       let shouldPublish: undefined | boolean;
@@ -187,32 +187,32 @@ export class ListAction extends BaseRushAction {
     console.log(JSON.stringify(output, undefined, 2));
   }
 
-  private _printList(selection: Set<RushConfigurationProject>): void {
+  #printList(selection: Set<RushConfigurationProject>): void {
     for (const project of selection) {
       // eslint-disable-next-line no-console
       console.log(project.packageName);
     }
   }
 
-  private async _printListTableAsync(selection: Set<RushConfigurationProject>): Promise<void> {
+  async #printListTableAsync(selection: Set<RushConfigurationProject>): Promise<void> {
     const tableHeader: string[] = ['Project'];
     if (this.rushConfiguration.subspacesFeatureEnabled) {
       tableHeader.push('Subspace');
     }
 
-    if (this._version.value || this._detailedFlag.value) {
+    if (this.#version.value || this.#detailedFlag.value) {
       tableHeader.push('Version');
     }
 
-    if (this._path.value || this._detailedFlag.value) {
+    if (this.#path.value || this.#detailedFlag.value) {
       tableHeader.push('Path');
     }
 
-    if (this._fullPath.value) {
+    if (this.#fullPath.value) {
       tableHeader.push('Full Path');
     }
 
-    if (this._detailedFlag.value) {
+    if (this.#detailedFlag.value) {
       tableHeader.push('Version policy');
       tableHeader.push('Version policy name');
       tableHeader.push('Should publish');
@@ -236,19 +236,19 @@ export class ListAction extends BaseRushAction {
         appendToPackageRow(project.subspace.subspaceName);
       }
 
-      if (this._version.value || this._detailedFlag.value) {
+      if (this.#version.value || this.#detailedFlag.value) {
         appendToPackageRow(project.packageJson.version);
       }
 
-      if (this._path.value || this._detailedFlag.value) {
+      if (this.#path.value || this.#detailedFlag.value) {
         appendToPackageRow(project.projectRelativeFolder);
       }
 
-      if (this._fullPath.value) {
+      if (this.#fullPath.value) {
         appendToPackageRow(project.projectFolder);
       }
 
-      if (this._detailedFlag.value) {
+      if (this.#detailedFlag.value) {
         // When we HAVE a version policy
         let versionPolicyDefinitionName: string = '';
         let versionPolicyName: string = '';
diff --git a/libraries/rush-lib/src/cli/actions/PublishAction.ts b/libraries/rush-lib/src/cli/actions/PublishAction.ts
index 4363f378cfe..877eeb4eca0 100644
--- a/libraries/rush-lib/src/cli/actions/PublishAction.ts
+++ b/libraries/rush-lib/src/cli/actions/PublishAction.ts
@@ -32,31 +32,31 @@ import { IS_WINDOWS } from '../../utilities/executionUtilities';
 import type { RushConfiguration } from '../../api/RushConfiguration';
 
 export class PublishAction extends BaseRushAction {
-  private readonly _addCommitDetails: CommandLineFlagParameter;
-  private readonly _apply: CommandLineFlagParameter;
-  private readonly _includeAll: CommandLineFlagParameter;
-  private readonly _npmAuthToken: CommandLineStringParameter;
-  private readonly _npmTag: CommandLineStringParameter;
-  private readonly _npmAccessLevel: CommandLineChoiceParameter;
-  private readonly _publish: CommandLineFlagParameter;
-  private readonly _regenerateChangelogs: CommandLineFlagParameter;
-  private readonly _registryUrl: CommandLineStringParameter;
-  private readonly _targetBranch: CommandLineStringParameter;
-  private readonly _prereleaseName: CommandLineStringParameter;
-  private readonly _partialPrerelease: CommandLineFlagParameter;
-  private readonly _suffix: CommandLineStringParameter;
-  private readonly _force: CommandLineFlagParameter;
-  private readonly _versionPolicy: CommandLineStringParameter;
-  private readonly _applyGitTagsOnPack: CommandLineFlagParameter;
-  private readonly _commitId: CommandLineStringParameter;
-  private readonly _releaseFolder: CommandLineStringParameter;
-  private readonly _pack: CommandLineFlagParameter;
-  private readonly _ignoreGitHooksParameter: CommandLineFlagParameter;
-
-  private _prereleaseToken!: PrereleaseToken;
-  private _hotfixTagOverride!: string;
-  private _targetNpmrcPublishFolder!: string;
-  private _targetNpmrcPublishPath!: string;
+  readonly #addCommitDetails: CommandLineFlagParameter;
+  readonly #apply: CommandLineFlagParameter;
+  readonly #includeAll: CommandLineFlagParameter;
+  readonly #npmAuthToken: CommandLineStringParameter;
+  readonly #npmTag: CommandLineStringParameter;
+  readonly #npmAccessLevel: CommandLineChoiceParameter;
+  readonly #publish: CommandLineFlagParameter;
+  readonly #regenerateChangelogs: CommandLineFlagParameter;
+  readonly #registryUrl: CommandLineStringParameter;
+  readonly #targetBranch: CommandLineStringParameter;
+  readonly #prereleaseName: CommandLineStringParameter;
+  readonly #partialPrerelease: CommandLineFlagParameter;
+  readonly #suffix: CommandLineStringParameter;
+  readonly #force: CommandLineFlagParameter;
+  readonly #versionPolicy: CommandLineStringParameter;
+  readonly #applyGitTagsOnPack: CommandLineFlagParameter;
+  readonly #commitId: CommandLineStringParameter;
+  readonly #releaseFolder: CommandLineStringParameter;
+  readonly #pack: CommandLineFlagParameter;
+  readonly #ignoreGitHooksParameter: CommandLineFlagParameter;
+
+  #prereleaseToken!: PrereleaseToken;
+  #hotfixTagOverride!: string;
+  #targetNpmrcPublishFolder!: string;
+  #targetNpmrcPublishPath!: string;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -69,12 +69,12 @@ export class PublishAction extends BaseRushAction {
       parser
     });
 
-    this._apply = this.defineFlagParameter({
+    this.#apply = this.defineFlagParameter({
       parameterLongName: '--apply',
       parameterShortName: '-a',
       description: 'If this flag is specified, the change requests will be applied to package.json files.'
     });
-    this._targetBranch = this.defineStringParameter({
+    this.#targetBranch = this.defineStringParameter({
       parameterLongName: '--target-branch',
       parameterShortName: '-b',
       argumentName: 'BRANCH',
@@ -82,24 +82,24 @@ export class PublishAction extends BaseRushAction {
         'If this flag is specified, applied changes and deleted change requests will be ' +
         'committed and merged into the target branch.'
     });
-    this._publish = this.defineFlagParameter({
+    this.#publish = this.defineFlagParameter({
       parameterLongName: '--publish',
       parameterShortName: '-p',
       description: 'If this flag is specified, applied changes will be published to the NPM registry.'
     });
-    this._addCommitDetails = this.defineFlagParameter({
+    this.#addCommitDetails = this.defineFlagParameter({
       parameterLongName: '--add-commit-details',
       parameterShortName: undefined,
       description: 'Adds commit author and hash to the changelog.json files for each change.'
     });
-    this._regenerateChangelogs = this.defineFlagParameter({
+    this.#regenerateChangelogs = this.defineFlagParameter({
       parameterLongName: '--regenerate-changelogs',
       parameterShortName: undefined,
       description: 'Regenerates all changelog files based on the current JSON content.'
     });
 
     // NPM registry related parameters
-    this._registryUrl = this.defineStringParameter({
+    this.#registryUrl = this.defineStringParameter({
       parameterLongName: '--registry',
       parameterShortName: '-r',
       argumentName: 'REGISTRY',
@@ -107,7 +107,7 @@ export class PublishAction extends BaseRushAction {
         `Publishes to a specified NPM registry. If this is specified, it will prevent the current commit will not be ` +
         'tagged.'
     });
-    this._npmAuthToken = this.defineStringParameter({
+    this.#npmAuthToken = this.defineStringParameter({
       parameterLongName: '--npm-auth-token',
       parameterShortName: '-n',
       argumentName: 'TOKEN',
@@ -117,7 +117,7 @@ export class PublishAction extends BaseRushAction {
         ' safer practice is to pass the token via an environment variable and reference it from your ' +
         ' common/config/rush/.npmrc-publish file.'
     });
-    this._npmTag = this.defineStringParameter({
+    this.#npmTag = this.defineStringParameter({
       parameterLongName: '--tag',
       parameterShortName: '-t',
       argumentName: 'TAG',
@@ -126,7 +126,7 @@ export class PublishAction extends BaseRushAction {
         `the package is older than the current latest, so in publishing workflows for older releases, providing ` +
         `a tag is important. When hotfix changes are made, this parameter defaults to 'hotfix'.`
     });
-    this._npmAccessLevel = this.defineChoiceParameter({
+    this.#npmAccessLevel = this.defineChoiceParameter({
       alternatives: ['public', 'restricted'],
       parameterLongName: '--set-access-level',
       parameterShortName: undefined,
@@ -139,13 +139,13 @@ export class PublishAction extends BaseRushAction {
     });
 
     // NPM pack tarball related parameters
-    this._pack = this.defineFlagParameter({
+    this.#pack = this.defineFlagParameter({
       parameterLongName: '--pack',
       description:
         `Packs projects into tarballs instead of publishing to npm repository. It can only be used when ` +
         `--include-all is specified. If this flag is specified, NPM registry related parameters will be ignored.`
     });
-    this._releaseFolder = this.defineStringParameter({
+    this.#releaseFolder = this.defineStringParameter({
       parameterLongName: '--release-folder',
       argumentName: 'FOLDER',
       description:
@@ -154,7 +154,7 @@ export class PublishAction extends BaseRushAction {
     });
     // End of NPM pack tarball related parameters
 
-    this._includeAll = this.defineFlagParameter({
+    this.#includeAll = this.defineFlagParameter({
       parameterLongName: '--include-all',
       parameterShortName: undefined,
       description:
@@ -162,42 +162,42 @@ export class PublishAction extends BaseRushAction {
         'or with a specified version policy ' +
         'will be published if their version is newer than published version.'
     });
-    this._versionPolicy = this.defineStringParameter({
+    this.#versionPolicy = this.defineStringParameter({
       parameterLongName: '--version-policy',
       argumentName: 'POLICY',
       description:
         'Version policy name. Only projects with this version policy will be published if used ' +
         'with --include-all.'
     });
-    this._prereleaseName = this.defineStringParameter({
+    this.#prereleaseName = this.defineStringParameter({
       parameterLongName: '--prerelease-name',
       argumentName: 'NAME',
       description:
         'Bump up to a prerelease version with the provided prerelease name. Cannot be used with --suffix'
     });
-    this._partialPrerelease = this.defineFlagParameter({
+    this.#partialPrerelease = this.defineFlagParameter({
       parameterLongName: '--partial-prerelease',
       parameterShortName: undefined,
       description:
         'Used with --prerelease-name. Only bump packages to a prerelease version if they have changes.'
     });
-    this._suffix = this.defineStringParameter({
+    this.#suffix = this.defineStringParameter({
       parameterLongName: '--suffix',
       argumentName: 'SUFFIX',
       description: 'Append a suffix to all changed versions. Cannot be used with --prerelease-name.'
     });
-    this._force = this.defineFlagParameter({
+    this.#force = this.defineFlagParameter({
       parameterLongName: '--force',
       parameterShortName: undefined,
       description: 'If this flag is specified with --publish, packages will be published with --force on npm'
     });
-    this._applyGitTagsOnPack = this.defineFlagParameter({
+    this.#applyGitTagsOnPack = this.defineFlagParameter({
       parameterLongName: '--apply-git-tags-on-pack',
       description:
         `If specified with --publish and --pack, git tags will be applied for packages` +
         ` as if a publish was being run without --pack.`
     });
-    this._commitId = this.defineStringParameter({
+    this.#commitId = this.defineStringParameter({
       parameterLongName: '--commit',
       parameterShortName: '-c',
       argumentName: 'COMMIT_ID',
@@ -205,7 +205,7 @@ export class PublishAction extends BaseRushAction {
         `Used in conjunction with git tagging -- apply git tags at the commit hash` +
         ` specified. If not provided, the current HEAD will be tagged.`
     });
-    this._ignoreGitHooksParameter = this.defineFlagParameter({
+    this.#ignoreGitHooksParameter = this.defineFlagParameter({
       parameterLongName: '--ignore-git-hooks',
       description: `Skips execution of all git hooks. Make sure you know what you are skipping.`
     });
@@ -225,35 +225,35 @@ export class PublishAction extends BaseRushAction {
     );
 
     // Example: "common\temp\publish-home"
-    this._targetNpmrcPublishFolder = path.join(this.rushConfiguration.commonTempFolder, 'publish-home');
+    this.#targetNpmrcPublishFolder = path.join(this.rushConfiguration.commonTempFolder, 'publish-home');
 
     // Example: "common\temp\publish-home\.npmrc"
-    this._targetNpmrcPublishPath = path.join(this._targetNpmrcPublishFolder, '.npmrc');
+    this.#targetNpmrcPublishPath = path.join(this.#targetNpmrcPublishFolder, '.npmrc');
 
     const allPackages: ReadonlyMap<string, RushConfigurationProject> = this.rushConfiguration.projectsByName;
 
-    if (this._regenerateChangelogs.value) {
+    if (this.#regenerateChangelogs.value) {
       // eslint-disable-next-line no-console
       console.log('Regenerating changelogs');
       ChangelogGenerator.regenerateChangelogs(allPackages, this.rushConfiguration);
       return;
     }
 
-    this._validate();
+    this.#validate();
 
-    this._addNpmPublishHome(this.rushConfiguration.isPnpm);
+    this.#addNpmPublishHome(this.rushConfiguration.isPnpm);
 
     const git: Git = new Git(this.rushConfiguration);
-    const publishGit: PublishGit = new PublishGit(git, this._targetBranch.value);
-    if (this._includeAll.value) {
-      await this._publishAllAsync(publishGit, allPackages);
+    const publishGit: PublishGit = new PublishGit(git, this.#targetBranch.value);
+    if (this.#includeAll.value) {
+      await this.#publishAllAsync(publishGit, allPackages);
     } else {
-      this._prereleaseToken = new PrereleaseToken(
-        this._prereleaseName.value,
-        this._suffix.value,
-        this._partialPrerelease.value
+      this.#prereleaseToken = new PrereleaseToken(
+        this.#prereleaseName.value,
+        this.#suffix.value,
+        this.#partialPrerelease.value
       );
-      await this._publishChangesAsync(git, publishGit, allPackages);
+      await this.#publishChangesAsync(git, publishGit, allPackages);
     }
 
     // eslint-disable-next-line no-console
@@ -263,25 +263,25 @@ export class PublishAction extends BaseRushAction {
   /**
    * Validate some input parameters
    */
-  private _validate(): void {
-    if (this._pack.value && !this._includeAll.value) {
+  #validate(): void {
+    if (this.#pack.value && !this.#includeAll.value) {
       throw new Error('--pack can only be used with --include-all');
     }
-    if (this._releaseFolder.value && !this._pack.value) {
+    if (this.#releaseFolder.value && !this.#pack.value) {
       throw new Error(`--release-folder can only be used with --pack`);
     }
-    if (this._applyGitTagsOnPack.value && !this._pack.value) {
-      throw new Error(`${this._applyGitTagsOnPack.longName} must be used with ${this._pack.longName}`);
+    if (this.#applyGitTagsOnPack.value && !this.#pack.value) {
+      throw new Error(`${this.#applyGitTagsOnPack.longName} must be used with ${this.#pack.longName}`);
     }
   }
 
-  private async _publishChangesAsync(
+  async #publishChangesAsync(
     git: Git,
     publishGit: PublishGit,
     allPackages: ReadonlyMap<string, RushConfigurationProject>
   ): Promise<void> {
     const changeManager: ChangeManager = new ChangeManager(this.rushConfiguration);
-    await changeManager.loadAsync(this._prereleaseToken, this._addCommitDetails.value);
+    await changeManager.loadAsync(this.#prereleaseToken, this.#addCommitDetails.value);
 
     if (changeManager.hasChanges()) {
       const orderedChanges: IChangeInfo[] = changeManager.packageChanges;
@@ -290,29 +290,29 @@ export class PublishAction extends BaseRushAction {
       // Make changes in temp branch.
       await publishGit.checkoutAsync(tempBranchName, true);
 
-      await this._setDependenciesBeforePublishAsync();
+      await this.#setDependenciesBeforePublishAsync();
 
       // Make changes to package.json and change logs.
-      changeManager.apply(this._apply.value);
-      await changeManager.updateChangelogAsync(this.terminal, this._apply.value);
+      changeManager.apply(this.#apply.value);
+      await changeManager.updateChangelogAsync(this.terminal, this.#apply.value);
 
-      await this._setDependenciesBeforeCommitAsync();
+      await this.#setDependenciesBeforeCommitAsync();
 
       if (await git.hasUncommittedChangesAsync()) {
         // Stage, commit, and push the changes to remote temp branch.
         await publishGit.addChangesAsync(':/*');
         await publishGit.commitAsync(
           this.rushConfiguration.gitVersionBumpCommitMessage || DEFAULT_PACKAGE_UPDATE_MESSAGE,
-          !this._ignoreGitHooksParameter.value
+          !this.#ignoreGitHooksParameter.value
         );
-        await publishGit.pushAsync(tempBranchName, !this._ignoreGitHooksParameter.value);
+        await publishGit.pushAsync(tempBranchName, !this.#ignoreGitHooksParameter.value);
 
-        await this._setDependenciesBeforePublishAsync();
+        await this.#setDependenciesBeforePublishAsync();
 
         // Override tag parameter if there is a hotfix change.
         for (const change of orderedChanges) {
           if (change.changeType === ChangeType.hotfix) {
-            this._hotfixTagOverride = 'hotfix';
+            this.#hotfixTagOverride = 'hotfix';
             break;
           }
         }
@@ -322,8 +322,8 @@ export class PublishAction extends BaseRushAction {
           if (change.changeType && change.changeType > ChangeType.dependency) {
             const project: RushConfigurationProject | undefined = allPackages.get(change.packageName);
             if (project) {
-              if (!(await this._packageExistsAsync(project))) {
-                await this._npmPublishAsync(change.packageName, project.publishFolder);
+              if (!(await this.#packageExistsAsync(project))) {
+                await this.#npmPublishAsync(change.packageName, project.publishFolder);
               } else {
                 // eslint-disable-next-line no-console
                 console.log(`Skip ${change.packageName}. Package exists.`);
@@ -335,38 +335,38 @@ export class PublishAction extends BaseRushAction {
           }
         }
 
-        await this._setDependenciesBeforeCommitAsync();
+        await this.#setDependenciesBeforeCommitAsync();
 
         // Create and push appropriate Git tags.
-        await this._gitAddTagsAsync(publishGit, orderedChanges);
-        await publishGit.pushAsync(tempBranchName, !this._ignoreGitHooksParameter.value);
+        await this.#gitAddTagsAsync(publishGit, orderedChanges);
+        await publishGit.pushAsync(tempBranchName, !this.#ignoreGitHooksParameter.value);
 
         // Now merge to target branch.
-        await publishGit.checkoutAsync(this._targetBranch.value!);
-        await publishGit.pullAsync(!this._ignoreGitHooksParameter.value);
-        await publishGit.mergeAsync(tempBranchName, !this._ignoreGitHooksParameter.value);
-        await publishGit.pushAsync(this._targetBranch.value!, !this._ignoreGitHooksParameter.value);
-        await publishGit.deleteBranchAsync(tempBranchName, true, !this._ignoreGitHooksParameter.value);
+        await publishGit.checkoutAsync(this.#targetBranch.value!);
+        await publishGit.pullAsync(!this.#ignoreGitHooksParameter.value);
+        await publishGit.mergeAsync(tempBranchName, !this.#ignoreGitHooksParameter.value);
+        await publishGit.pushAsync(this.#targetBranch.value!, !this.#ignoreGitHooksParameter.value);
+        await publishGit.deleteBranchAsync(tempBranchName, true, !this.#ignoreGitHooksParameter.value);
       } else {
-        await publishGit.checkoutAsync(this._targetBranch.value!);
-        await publishGit.deleteBranchAsync(tempBranchName, false, !this._ignoreGitHooksParameter.value);
+        await publishGit.checkoutAsync(this.#targetBranch.value!);
+        await publishGit.deleteBranchAsync(tempBranchName, false, !this.#ignoreGitHooksParameter.value);
       }
     }
   }
 
-  private async _publishAllAsync(
+  async #publishAllAsync(
     git: PublishGit,
     allPackages: ReadonlyMap<string, RushConfigurationProject>
   ): Promise<void> {
     // eslint-disable-next-line no-console
-    console.log(`Rush publish starts with includeAll and version policy ${this._versionPolicy.value}`);
+    console.log(`Rush publish starts with includeAll and version policy ${this.#versionPolicy.value}`);
 
     let updated: boolean = false;
 
     for (const [packageName, packageConfig] of allPackages) {
       if (
         packageConfig.shouldPublish &&
-        (!this._versionPolicy.value || this._versionPolicy.value === packageConfig.versionPolicyName)
+        (!this.#versionPolicy.value || this.#versionPolicy.value === packageConfig.versionPolicyName)
       ) {
         const applyTagAsync: (apply: boolean) => Promise<void> = async (apply: boolean): Promise<void> => {
           if (!apply) {
@@ -385,22 +385,22 @@ export class PublishAction extends BaseRushAction {
           }
 
           await git.addTagAsync(
-            !!this._publish.value,
+            !!this.#publish.value,
             packageName,
             packageVersion,
-            this._commitId.value,
-            this._prereleaseName.value
+            this.#commitId.value,
+            this.#prereleaseName.value
           );
           updated = true;
         };
 
-        if (this._pack.value) {
+        if (this.#pack.value) {
           // packs to tarball instead of publishing to NPM repository
-          await this._npmPackAsync(packageName, packageConfig);
-          await applyTagAsync(this._applyGitTagsOnPack.value);
-        } else if (this._force.value || !(await this._packageExistsAsync(packageConfig))) {
+          await this.#npmPackAsync(packageName, packageConfig);
+          await applyTagAsync(this.#applyGitTagsOnPack.value);
+        } else if (this.#force.value || !(await this.#packageExistsAsync(packageConfig))) {
           // Publish to npm repository
-          await this._npmPublishAsync(packageName, packageConfig.publishFolder);
+          await this.#npmPublishAsync(packageName, packageConfig.publishFolder);
           await applyTagAsync(true);
         } else {
           // eslint-disable-next-line no-console
@@ -410,11 +410,11 @@ export class PublishAction extends BaseRushAction {
     }
 
     if (updated) {
-      await git.pushAsync(this._targetBranch.value!, !this._ignoreGitHooksParameter.value);
+      await git.pushAsync(this.#targetBranch.value!, !this.#ignoreGitHooksParameter.value);
     }
   }
 
-  private async _gitAddTagsAsync(git: PublishGit, orderedChanges: IChangeInfo[]): Promise<void> {
+  async #gitAddTagsAsync(git: PublishGit, orderedChanges: IChangeInfo[]): Promise<void> {
     for (const change of orderedChanges) {
       if (
         change.changeType &&
@@ -422,35 +422,35 @@ export class PublishAction extends BaseRushAction {
         this.rushConfiguration.projectsByName.get(change.packageName)!.shouldPublish
       ) {
         await git.addTagAsync(
-          !!this._publish.value && !this._registryUrl.value,
+          !!this.#publish.value && !this.#registryUrl.value,
           change.packageName,
           change.newVersion!,
-          this._commitId.value,
-          this._prereleaseName.value
+          this.#commitId.value,
+          this.#prereleaseName.value
         );
       }
     }
   }
 
-  private async _npmPublishAsync(packageName: string, packagePath: string): Promise<void> {
+  async #npmPublishAsync(packageName: string, packagePath: string): Promise<void> {
     const env: { [key: string]: string | undefined } = PublishUtilities.getEnvArgs();
     const args: string[] = ['publish'];
 
     if (this.rushConfiguration.projectsByName.get(packageName)!.shouldPublish) {
-      this._addSharedNpmConfig(env, args);
+      this.#addSharedNpmConfig(env, args);
 
-      if (this._npmTag.value) {
-        args.push(`--tag`, this._npmTag.value);
-      } else if (this._hotfixTagOverride) {
-        args.push(`--tag`, this._hotfixTagOverride);
+      if (this.#npmTag.value) {
+        args.push(`--tag`, this.#npmTag.value);
+      } else if (this.#hotfixTagOverride) {
+        args.push(`--tag`, this.#hotfixTagOverride);
       }
 
-      if (this._force.value) {
+      if (this.#force.value) {
         args.push(`--force`);
       }
 
-      if (this._npmAccessLevel.value) {
-        args.push(`--access`, this._npmAccessLevel.value);
+      if (this.#npmAccessLevel.value) {
+        args.push(`--access`, this.#npmAccessLevel.value);
       }
 
       if (this.rushConfiguration.isPnpm) {
@@ -468,10 +468,10 @@ export class PublishAction extends BaseRushAction {
           : this.rushConfiguration.packageManagerToolFilename;
 
       // If the auth token was specified via the command line, avoid printing it on the console
-      const secretSubstring: string | undefined = this._npmAuthToken.value;
+      const secretSubstring: string | undefined = this.#npmAuthToken.value;
 
       await PublishUtilities.execCommandAsync({
-        shouldExecute: this._publish.value,
+        shouldExecute: this.#publish.value,
         command: packageManagerToolFilename,
         args,
         workingDirectory: packagePath,
@@ -481,10 +481,10 @@ export class PublishAction extends BaseRushAction {
     }
   }
 
-  private async _packageExistsAsync(packageConfig: RushConfigurationProject): Promise<boolean> {
+  async #packageExistsAsync(packageConfig: RushConfigurationProject): Promise<boolean> {
     const env: { [key: string]: string | undefined } = PublishUtilities.getEnvArgs();
     const args: string[] = [];
-    this._addSharedNpmConfig(env, args);
+    this.#addSharedNpmConfig(env, args);
 
     const publishedVersions: string[] = await Npm.getPublishedVersionsAsync(
       packageConfig.packageName,
@@ -515,24 +515,24 @@ export class PublishAction extends BaseRushAction {
     return publishedVersions.indexOf(normalizedVersion) >= 0;
   }
 
-  private async _npmPackAsync(packageName: string, project: RushConfigurationProject): Promise<void> {
+  async #npmPackAsync(packageName: string, project: RushConfigurationProject): Promise<void> {
     const args: string[] = ['pack'];
     const env: { [key: string]: string | undefined } = PublishUtilities.getEnvArgs();
 
     await PublishUtilities.execCommandAsync({
-      shouldExecute: this._publish.value,
+      shouldExecute: this.#publish.value,
       command: this.rushConfiguration.packageManagerToolFilename,
       args,
       workingDirectory: project.publishFolder,
       environment: env
     });
 
-    if (this._publish.value) {
+    if (this.#publish.value) {
       // Copy the tarball the release folder
-      const tarballName: string = this._calculateTarballName(project);
+      const tarballName: string = this.#calculateTarballName(project);
       const tarballPath: string = path.join(project.publishFolder, tarballName);
-      const destFolder: string = this._releaseFolder.value
-        ? this._releaseFolder.value
+      const destFolder: string = this.#releaseFolder.value
+        ? this.#releaseFolder.value
         : path.join(this.rushConfiguration.commonTempFolder, 'artifacts', 'packages');
 
       FileSystem.move({
@@ -543,7 +543,7 @@ export class PublishAction extends BaseRushAction {
     }
   }
 
-  private _calculateTarballName(project: RushConfigurationProject): string {
+  #calculateTarballName(project: RushConfigurationProject): string {
     // Same logic as how npm forms the tarball name
     const packageName: string = project.packageName;
     const name: string = packageName[0] === '@' ? packageName.substr(1).replace(/\//g, '-') : packageName;
@@ -556,12 +556,12 @@ export class PublishAction extends BaseRushAction {
     }
   }
 
-  private async _setDependenciesBeforePublishAsync(): Promise<void> {
+  async #setDependenciesBeforePublishAsync(): Promise<void> {
     const rushConfiguration: RushConfiguration = this.rushConfiguration;
     await Async.forEachAsync(
       rushConfiguration.projects,
       async ({ versionPolicy, versionPolicyName, packageName }) => {
-        if (!this._versionPolicy.value || this._versionPolicy.value === versionPolicyName) {
+        if (!this.#versionPolicy.value || this.#versionPolicy.value === versionPolicyName) {
           await versionPolicy?.setDependenciesBeforePublishAsync(packageName, rushConfiguration);
         }
       },
@@ -569,12 +569,12 @@ export class PublishAction extends BaseRushAction {
     );
   }
 
-  private async _setDependenciesBeforeCommitAsync(): Promise<void> {
+  async #setDependenciesBeforeCommitAsync(): Promise<void> {
     const rushConfiguration: RushConfiguration = this.rushConfiguration;
     await Async.forEachAsync(
       rushConfiguration.projects,
       async ({ versionPolicy, versionPolicyName, packageName }) => {
-        if (!this._versionPolicy.value || this._versionPolicy.value === versionPolicyName) {
+        if (!this.#versionPolicy.value || this.#versionPolicy.value === versionPolicyName) {
           await versionPolicy?.setDependenciesBeforeCommitAsync(packageName, rushConfiguration);
         }
       },
@@ -582,38 +582,38 @@ export class PublishAction extends BaseRushAction {
     );
   }
 
-  private _addNpmPublishHome(supportEnvVarFallbackSyntax: boolean): void {
+  #addNpmPublishHome(supportEnvVarFallbackSyntax: boolean): void {
     // Create "common\temp\publish-home" folder, if it doesn't exist
-    Utilities.createFolderWithRetry(this._targetNpmrcPublishFolder);
+    Utilities.createFolderWithRetry(this.#targetNpmrcPublishFolder);
 
     // Copy down the committed "common\config\rush\.npmrc-publish" file, if there is one
     Utilities.syncNpmrc({
       sourceNpmrcFolder: this.rushConfiguration.commonRushConfigFolder,
-      targetNpmrcFolder: this._targetNpmrcPublishFolder,
+      targetNpmrcFolder: this.#targetNpmrcPublishFolder,
       useNpmrcPublish: true,
       supportEnvVarFallbackSyntax
     });
   }
 
-  private _addSharedNpmConfig(env: { [key: string]: string | undefined }, args: string[]): void {
+  #addSharedNpmConfig(env: { [key: string]: string | undefined }, args: string[]): void {
     const userHomeEnvVariable: string = IS_WINDOWS ? 'USERPROFILE' : 'HOME';
     let registry: string = '//registry.npmjs.org/';
 
     // Check if .npmrc file exists in "common\temp\publish-home"
-    if (FileSystem.exists(this._targetNpmrcPublishPath)) {
+    if (FileSystem.exists(this.#targetNpmrcPublishPath)) {
       // Redirect userHomeEnvVariable, NPM will use config in "common\temp\publish-home\.npmrc"
-      env[userHomeEnvVariable] = this._targetNpmrcPublishFolder;
+      env[userHomeEnvVariable] = this.#targetNpmrcPublishFolder;
     }
 
     // Check if registryUrl and token are specified via command-line
-    if (this._registryUrl.value) {
-      const registryUrl: string = this._registryUrl.value;
+    if (this.#registryUrl.value) {
+      const registryUrl: string = this.#registryUrl.value;
       env['npm_config_registry'] = registryUrl; // eslint-disable-line dot-notation
       registry = registryUrl.substring(registryUrl.indexOf('//'));
     }
 
-    if (this._npmAuthToken.value) {
-      args.push(`--${registry}:_authToken=${this._npmAuthToken.value}`);
+    if (this.#npmAuthToken.value) {
+      args.push(`--${registry}:_authToken=${this.#npmAuthToken.value}`);
     }
   }
 }
diff --git a/libraries/rush-lib/src/cli/actions/PurgeAction.ts b/libraries/rush-lib/src/cli/actions/PurgeAction.ts
index 3f8e0d223ff..00a3c6b485a 100644
--- a/libraries/rush-lib/src/cli/actions/PurgeAction.ts
+++ b/libraries/rush-lib/src/cli/actions/PurgeAction.ts
@@ -12,7 +12,7 @@ import { UnlinkManager } from '../../logic/UnlinkManager';
 import { PURGE_ACTION_NAME } from '../../utilities/actionNameConstants';
 
 export class PurgeAction extends BaseRushAction {
-  private readonly _unsafeParameter: CommandLineFlagParameter;
+  readonly #unsafeParameter: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -25,7 +25,7 @@ export class PurgeAction extends BaseRushAction {
       parser
     });
 
-    this._unsafeParameter = this.defineFlagParameter({
+    this.#unsafeParameter = this.defineFlagParameter({
       parameterLongName: '--unsafe',
       description:
         '(UNSAFE!) Also delete shared files such as the package manager instances stored in' +
@@ -42,7 +42,7 @@ export class PurgeAction extends BaseRushAction {
 
     await unlinkManager.unlinkAsync(/*force:*/ true);
 
-    if (this._unsafeParameter.value!) {
+    if (this.#unsafeParameter.value!) {
       purgeManager.purgeUnsafe();
     } else {
       purgeManager.purgeNormal();
diff --git a/libraries/rush-lib/src/cli/actions/ScanAction.ts b/libraries/rush-lib/src/cli/actions/ScanAction.ts
index 3fd04e7a12e..5f634b32dcd 100644
--- a/libraries/rush-lib/src/cli/actions/ScanAction.ts
+++ b/libraries/rush-lib/src/cli/actions/ScanAction.ts
@@ -27,8 +27,8 @@ export interface IJsonOutput {
 }
 
 export class ScanAction extends BaseConfiglessRushAction {
-  private readonly _jsonFlag: CommandLineFlagParameter;
-  private readonly _allFlag: CommandLineFlagParameter;
+  readonly #jsonFlag: CommandLineFlagParameter;
+  readonly #allFlag: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -49,11 +49,11 @@ export class ScanAction extends BaseConfiglessRushAction {
       parser
     });
 
-    this._jsonFlag = this.defineFlagParameter({
+    this.#jsonFlag = this.defineFlagParameter({
       parameterLongName: '--json',
       description: 'If this flag is specified, output will be in JSON format.'
     });
-    this._allFlag = this.defineFlagParameter({
+    this.#allFlag = this.defineFlagParameter({
       parameterLongName: '--all',
       description: 'If this flag is specified, output will list all detected dependencies.'
     });
@@ -207,10 +207,10 @@ export class ScanAction extends BaseConfiglessRushAction {
       unusedDependencies: unusedDependencies
     };
 
-    if (this._jsonFlag.value) {
+    if (this.#jsonFlag.value) {
       // eslint-disable-next-line no-console
       console.log(JSON.stringify(output, undefined, 2));
-    } else if (this._allFlag.value) {
+    } else if (this.#allFlag.value) {
       if (detectedPackageNames.length !== 0) {
         // eslint-disable-next-line no-console
         console.log('Dependencies that seem to be imported by this project:');
diff --git a/libraries/rush-lib/src/cli/actions/UpdateAction.ts b/libraries/rush-lib/src/cli/actions/UpdateAction.ts
index 5fc74900e09..ead2347597d 100644
--- a/libraries/rush-lib/src/cli/actions/UpdateAction.ts
+++ b/libraries/rush-lib/src/cli/actions/UpdateAction.ts
@@ -12,8 +12,8 @@ import type { Subspace } from '../../api/Subspace';
 import { getVariantAsync } from '../../api/Variants';
 
 export class UpdateAction extends BaseInstallAction {
-  private readonly _fullParameter: CommandLineFlagParameter;
-  private readonly _recheckParameter: CommandLineFlagParameter;
+  readonly #fullParameter: CommandLineFlagParameter;
+  readonly #recheckParameter: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -50,7 +50,7 @@ export class UpdateAction extends BaseInstallAction {
       });
     }
 
-    this._fullParameter = this.defineFlagParameter({
+    this.#fullParameter = this.defineFlagParameter({
       parameterLongName: '--full',
       description:
         'Normally "rush update" tries to preserve your existing installed versions' +
@@ -60,7 +60,7 @@ export class UpdateAction extends BaseInstallAction {
         ' to the latest SemVer-compatible version.  This should be done periodically by a person' +
         ' or robot whose role is to deal with potential upgrade regressions.'
     });
-    this._recheckParameter = this.defineFlagParameter({
+    this.#recheckParameter = this.defineFlagParameter({
       parameterLongName: '--recheck',
       description:
         'If the shrinkwrap file appears to already satisfy the package.json files,' +
@@ -98,8 +98,8 @@ export class UpdateAction extends BaseInstallAction {
       bypassPolicyAllowed: true,
       bypassPolicy: this._bypassPolicyParameter.value!,
       noLink: this._noLinkParameter.value!,
-      fullUpgrade: this._fullParameter.value!,
-      recheckShrinkwrap: this._recheckParameter.value!,
+      fullUpgrade: this.#fullParameter.value!,
+      recheckShrinkwrap: this.#recheckParameter.value!,
       offline: this._offlineParameter.value!,
       networkConcurrency: this._networkConcurrencyParameter.value,
       collectLogFile: this._debugPackageManagerParameter.value!,
diff --git a/libraries/rush-lib/src/cli/actions/UpdateCloudCredentialsAction.ts b/libraries/rush-lib/src/cli/actions/UpdateCloudCredentialsAction.ts
index 97a792c9916..40f6b660eb3 100644
--- a/libraries/rush-lib/src/cli/actions/UpdateCloudCredentialsAction.ts
+++ b/libraries/rush-lib/src/cli/actions/UpdateCloudCredentialsAction.ts
@@ -11,9 +11,9 @@ import { BuildCacheConfiguration } from '../../api/BuildCacheConfiguration';
 import { RushConstants } from '../../logic/RushConstants';
 
 export class UpdateCloudCredentialsAction extends BaseRushAction {
-  private readonly _interactiveModeFlag: CommandLineFlagParameter;
-  private readonly _credentialParameter: CommandLineStringParameter;
-  private readonly _deleteFlag: CommandLineFlagParameter;
+  readonly #interactiveModeFlag: CommandLineFlagParameter;
+  readonly #credentialParameter: CommandLineStringParameter;
+  readonly #deleteFlag: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -26,17 +26,17 @@ export class UpdateCloudCredentialsAction extends BaseRushAction {
       parser
     });
 
-    this._interactiveModeFlag = this.defineFlagParameter({
+    this.#interactiveModeFlag = this.defineFlagParameter({
       parameterLongName: '--interactive',
       parameterShortName: '-i',
       description: 'Run the credential update operation in interactive mode, if supported by the provider.'
     });
-    this._credentialParameter = this.defineStringParameter({
+    this.#credentialParameter = this.defineStringParameter({
       parameterLongName: '--credential',
       argumentName: 'CREDENTIAL_STRING',
       description: 'A static credential, to be cached.'
     });
-    this._deleteFlag = this.defineFlagParameter({
+    this.#deleteFlag = this.defineFlagParameter({
       parameterLongName: '--delete',
       parameterShortName: '-d',
       description: 'If specified, delete stored credentials.'
@@ -53,10 +53,10 @@ export class UpdateCloudCredentialsAction extends BaseRushAction {
         this.rushSession
       );
 
-    if (this._deleteFlag.value) {
-      if (this._interactiveModeFlag.value || this._credentialParameter.value !== undefined) {
+    if (this.#deleteFlag.value) {
+      if (this.#interactiveModeFlag.value || this.#credentialParameter.value !== undefined) {
         terminal.writeErrorLine(
-          `If the ${this._deleteFlag.longName} is provided, no other parameters may be provided.`
+          `If the ${this.#deleteFlag.longName} is provided, no other parameters may be provided.`
         );
         throw new AlreadyReportedError();
       } else if (buildCacheConfiguration.cloudCacheProvider) {
@@ -64,24 +64,24 @@ export class UpdateCloudCredentialsAction extends BaseRushAction {
       } else {
         terminal.writeLine('A cloud build cache is not configured; there is nothing to delete.');
       }
-    } else if (this._interactiveModeFlag.value && this._credentialParameter.value !== undefined) {
+    } else if (this.#interactiveModeFlag.value && this.#credentialParameter.value !== undefined) {
       terminal.writeErrorLine(
-        `Both the ${this._interactiveModeFlag.longName} and the ` +
-          `${this._credentialParameter.longName} parameters were provided. Only one ` +
+        `Both the ${this.#interactiveModeFlag.longName} and the ` +
+          `${this.#credentialParameter.longName} parameters were provided. Only one ` +
           'or the other may be used at a time.'
       );
       throw new AlreadyReportedError();
-    } else if (this._interactiveModeFlag.value) {
+    } else if (this.#interactiveModeFlag.value) {
       if (buildCacheConfiguration.cloudCacheProvider) {
         await buildCacheConfiguration.cloudCacheProvider.updateCachedCredentialInteractiveAsync(terminal);
       } else {
         terminal.writeLine('A cloud build cache is not configured. Credentials are not required.');
       }
-    } else if (this._credentialParameter.value !== undefined) {
+    } else if (this.#credentialParameter.value !== undefined) {
       if (buildCacheConfiguration.cloudCacheProvider) {
         await buildCacheConfiguration.cloudCacheProvider.updateCachedCredentialAsync(
           terminal,
-          this._credentialParameter.value
+          this.#credentialParameter.value
         );
       } else {
         terminal.writeErrorLine('A cloud build cache is not configured. Credentials are not supported.');
@@ -89,9 +89,9 @@ export class UpdateCloudCredentialsAction extends BaseRushAction {
       }
     } else {
       terminal.writeErrorLine(
-        `One of the ${this._interactiveModeFlag.longName} parameter, the ` +
-          `${this._credentialParameter.longName} parameter, or the ` +
-          `${this._deleteFlag.longName} parameter must be provided.`
+        `One of the ${this.#interactiveModeFlag.longName} parameter, the ` +
+          `${this.#credentialParameter.longName} parameter, or the ` +
+          `${this.#deleteFlag.longName} parameter must be provided.`
       );
       throw new AlreadyReportedError();
     }
diff --git a/libraries/rush-lib/src/cli/actions/UpgradeInteractiveAction.ts b/libraries/rush-lib/src/cli/actions/UpgradeInteractiveAction.ts
index 273b67ba91b..e589e21e90a 100644
--- a/libraries/rush-lib/src/cli/actions/UpgradeInteractiveAction.ts
+++ b/libraries/rush-lib/src/cli/actions/UpgradeInteractiveAction.ts
@@ -10,9 +10,9 @@ import type * as InteractiveUpgraderType from '../../logic/InteractiveUpgrader';
 import { getVariantAsync, VARIANT_PARAMETER } from '../../api/Variants';
 
 export class UpgradeInteractiveAction extends BaseRushAction {
-  private _makeConsistentFlag: CommandLineFlagParameter;
-  private _skipUpdateFlag: CommandLineFlagParameter;
-  private readonly _variantParameter: CommandLineStringParameter;
+  #makeConsistentFlag: CommandLineFlagParameter;
+  #skipUpdateFlag: CommandLineFlagParameter;
+  readonly #variantParameter: CommandLineStringParameter;
 
   public constructor(parser: RushCommandLineParser) {
     const documentation: string[] = [
@@ -32,20 +32,20 @@ export class UpgradeInteractiveAction extends BaseRushAction {
       parser
     });
 
-    this._makeConsistentFlag = this.defineFlagParameter({
+    this.#makeConsistentFlag = this.defineFlagParameter({
       parameterLongName: '--make-consistent',
       description:
         'When upgrading dependencies from a single project, also upgrade dependencies from other projects.'
     });
 
-    this._skipUpdateFlag = this.defineFlagParameter({
+    this.#skipUpdateFlag = this.defineFlagParameter({
       parameterLongName: '--skip-update',
       parameterShortName: '-s',
       description:
         'If specified, the "rush update" command will not be run after updating the package.json files.'
     });
 
-    this._variantParameter = this.defineStringParameter(VARIANT_PARAMETER);
+    this.#variantParameter = this.defineStringParameter(VARIANT_PARAMETER);
   }
 
   public async runAsync(): Promise<void> {
@@ -64,13 +64,13 @@ export class UpgradeInteractiveAction extends BaseRushAction {
     );
 
     const variant: string | undefined = await getVariantAsync(
-      this._variantParameter,
+      this.#variantParameter,
       this.rushConfiguration,
       true
     );
     const shouldMakeConsistent: boolean =
       this.rushConfiguration.defaultSubspace.shouldEnsureConsistentVersions(variant) ||
-      this._makeConsistentFlag.value;
+      this.#makeConsistentFlag.value;
 
     const { projects, depsToUpgrade } = await interactiveUpgrader.upgradeAsync();
 
@@ -78,7 +78,7 @@ export class UpgradeInteractiveAction extends BaseRushAction {
       projects,
       packagesToAdd: depsToUpgrade.packages,
       updateOtherPackages: shouldMakeConsistent,
-      skipUpdate: this._skipUpdateFlag.value,
+      skipUpdate: this.#skipUpdateFlag.value,
       debugInstall: this.parser.isDebug,
       variant
     });
diff --git a/libraries/rush-lib/src/cli/actions/VersionAction.ts b/libraries/rush-lib/src/cli/actions/VersionAction.ts
index 6eff2c1176d..97e21909acd 100644
--- a/libraries/rush-lib/src/cli/actions/VersionAction.ts
+++ b/libraries/rush-lib/src/cli/actions/VersionAction.ts
@@ -22,15 +22,15 @@ export const DEFAULT_PACKAGE_UPDATE_MESSAGE: string = 'Bump versions [skip ci]';
 export const DEFAULT_CHANGELOG_UPDATE_MESSAGE: string = 'Update changelogs [skip ci]';
 
 export class VersionAction extends BaseRushAction {
-  private readonly _ensureVersionPolicy: CommandLineFlagParameter;
-  private readonly _overrideVersion: CommandLineStringParameter;
-  private readonly _bumpVersion: CommandLineFlagParameter;
-  private readonly _versionPolicy: CommandLineStringParameter;
-  private readonly _bypassPolicy: CommandLineFlagParameter;
-  private readonly _targetBranch: CommandLineStringParameter;
-  private readonly _overwriteBump: CommandLineStringParameter;
-  private readonly _prereleaseIdentifier: CommandLineStringParameter;
-  private readonly _ignoreGitHooksParameter: CommandLineFlagParameter;
+  readonly #ensureVersionPolicy: CommandLineFlagParameter;
+  readonly #overrideVersion: CommandLineStringParameter;
+  readonly #bumpVersion: CommandLineFlagParameter;
+  readonly #versionPolicy: CommandLineStringParameter;
+  readonly #bypassPolicy: CommandLineFlagParameter;
+  readonly #targetBranch: CommandLineStringParameter;
+  readonly #overwriteBump: CommandLineStringParameter;
+  readonly #prereleaseIdentifier: CommandLineStringParameter;
+  readonly #ignoreGitHooksParameter: CommandLineFlagParameter;
 
   public constructor(parser: RushCommandLineParser) {
     super({
@@ -40,37 +40,37 @@ export class VersionAction extends BaseRushAction {
       parser
     });
 
-    this._targetBranch = this.defineStringParameter({
+    this.#targetBranch = this.defineStringParameter({
       parameterLongName: '--target-branch',
       parameterShortName: '-b',
       argumentName: 'BRANCH',
       description: 'If this flag is specified, changes will be committed and merged into the target branch.'
     });
-    this._ensureVersionPolicy = this.defineFlagParameter({
+    this.#ensureVersionPolicy = this.defineFlagParameter({
       parameterLongName: '--ensure-version-policy',
       description: 'Updates package versions if needed to satisfy version policies.'
     });
-    this._overrideVersion = this.defineStringParameter({
+    this.#overrideVersion = this.defineStringParameter({
       parameterLongName: '--override-version',
       argumentName: 'NEW_VERSION',
       description:
         'Override the version in the specified --version-policy. ' +
         'This setting only works for lock-step version policy and when --ensure-version-policy is specified.'
     });
-    this._bumpVersion = this.defineFlagParameter({
+    this.#bumpVersion = this.defineFlagParameter({
       parameterLongName: '--bump',
       description: 'Bumps package version based on version policies.'
     });
-    this._bypassPolicy = this.defineFlagParameter({
+    this.#bypassPolicy = this.defineFlagParameter({
       parameterLongName: RushConstants.bypassPolicyFlagLongName,
       description: 'Overrides "gitPolicy" enforcement (use honorably!)'
     });
-    this._versionPolicy = this.defineStringParameter({
+    this.#versionPolicy = this.defineStringParameter({
       parameterLongName: '--version-policy',
       argumentName: 'POLICY',
       description: 'The name of the version policy'
     });
-    this._overwriteBump = this.defineStringParameter({
+    this.#overwriteBump = this.defineStringParameter({
       parameterLongName: '--override-bump',
       argumentName: 'BUMPTYPE',
       description:
@@ -78,7 +78,7 @@ export class VersionAction extends BaseRushAction {
         'Valid BUMPTYPE values include: prerelease, patch, preminor, minor, major. ' +
         'This setting only works for lock-step version policy in bump action.'
     });
-    this._prereleaseIdentifier = this.defineStringParameter({
+    this.#prereleaseIdentifier = this.defineStringParameter({
       parameterLongName: '--override-prerelease-id',
       argumentName: 'ID',
       description:
@@ -88,7 +88,7 @@ export class VersionAction extends BaseRushAction {
         'This setting increases to new prerelease id when "--bump" is provided but only replaces the ' +
         'prerelease name when "--ensure-version-policy" is provided.'
     });
-    this._ignoreGitHooksParameter = this.defineFlagParameter({
+    this.#ignoreGitHooksParameter = this.defineFlagParameter({
       parameterLongName: '--ignore-git-hooks',
       description: `Skips execution of all git hooks. Make sure you know what you are skipping.`
     });
@@ -100,13 +100,13 @@ export class VersionAction extends BaseRushAction {
     for (const subspace of this.rushConfiguration.subspaces) {
       await PolicyValidator.validatePolicyAsync(this.rushConfiguration, subspace, currentlyInstalledVariant, {
         bypassPolicyAllowed: true,
-        bypassPolicy: this._bypassPolicy.value
+        bypassPolicy: this.#bypassPolicy.value
       });
     }
     const git: Git = new Git(this.rushConfiguration);
     const userEmail: string = await git.getGitEmailAsync();
 
-    this._validateInput();
+    this.#validateInput();
     const versionManagerModule: typeof VersionManagerType = await import(
       /* webpackChunkName: 'VersionManager' */
       '../../logic/VersionManager'
@@ -117,76 +117,76 @@ export class VersionAction extends BaseRushAction {
       this.rushConfiguration.versionPolicyConfiguration
     );
 
-    if (this._ensureVersionPolicy.value) {
-      this._overwritePolicyVersionIfNeeded();
+    if (this.#ensureVersionPolicy.value) {
+      this.#overwritePolicyVersionIfNeeded();
       const tempBranch: string = 'version/ensure-' + new Date().getTime();
       versionManager.ensure(
-        this._versionPolicy.value,
+        this.#versionPolicy.value,
         true,
-        !!this._overrideVersion.value || !!this._prereleaseIdentifier.value
+        !!this.#overrideVersion.value || !!this.#prereleaseIdentifier.value
       );
 
       const updatedPackages: Map<string, IPackageJson> = versionManager.updatedProjects;
       if (updatedPackages.size > 0) {
         // eslint-disable-next-line no-console
         console.log(`${updatedPackages.size} packages are getting updated.`);
-        await this._gitProcessAsync(tempBranch, this._targetBranch.value, currentlyInstalledVariant);
+        await this.#gitProcessAsync(tempBranch, this.#targetBranch.value, currentlyInstalledVariant);
       }
-    } else if (this._bumpVersion.value) {
+    } else if (this.#bumpVersion.value) {
       const tempBranch: string = 'version/bump-' + new Date().getTime();
       await versionManager.bumpAsync(
         this.terminal,
-        this._versionPolicy.value,
-        this._overwriteBump.value ? Enum.getValueByKey(BumpType, this._overwriteBump.value) : undefined,
-        this._prereleaseIdentifier.value,
+        this.#versionPolicy.value,
+        this.#overwriteBump.value ? Enum.getValueByKey(BumpType, this.#overwriteBump.value) : undefined,
+        this.#prereleaseIdentifier.value,
         true
       );
-      await this._gitProcessAsync(tempBranch, this._targetBranch.value, currentlyInstalledVariant);
+      await this.#gitProcessAsync(tempBranch, this.#targetBranch.value, currentlyInstalledVariant);
     }
   }
 
-  private _overwritePolicyVersionIfNeeded(): void {
-    if (!this._overrideVersion.value && !this._prereleaseIdentifier.value) {
+  #overwritePolicyVersionIfNeeded(): void {
+    if (!this.#overrideVersion.value && !this.#prereleaseIdentifier.value) {
       // No need to overwrite policy version
       return;
     }
-    if (this._overrideVersion.value && this._prereleaseIdentifier.value) {
+    if (this.#overrideVersion.value && this.#prereleaseIdentifier.value) {
       throw new Error(
         `The parameters "--override-version" and "--override-prerelease-id" cannot be used together.`
       );
     }
 
-    if (this._versionPolicy.value) {
+    if (this.#versionPolicy.value) {
       const versionConfig: VersionPolicyConfiguration = this.rushConfiguration.versionPolicyConfiguration;
       const policy: LockStepVersionPolicy = versionConfig.getVersionPolicy(
-        this._versionPolicy.value
+        this.#versionPolicy.value
       ) as LockStepVersionPolicy;
       if (!policy || !policy.isLockstepped) {
         throw new Error(`The lockstep version policy "${policy.policyName}" is not found.`);
       }
       let newVersion: string | undefined = undefined;
-      if (this._overrideVersion.value) {
-        newVersion = this._overrideVersion.value;
-      } else if (this._prereleaseIdentifier.value) {
+      if (this.#overrideVersion.value) {
+        newVersion = this.#overrideVersion.value;
+      } else if (this.#prereleaseIdentifier.value) {
         const newPolicyVersion: semver.SemVer = new semver.SemVer(policy.version);
         if (newPolicyVersion.prerelease.length) {
           // Update 1.5.0-alpha.10 to 1.5.0-beta.10
           // For example, if we are parsing "1.5.0-alpha.10" then the newPolicyVersion.prerelease array
           // would contain [ "alpha", 10 ], so we would replace "alpha" with "beta"
           newPolicyVersion.prerelease = [
-            this._prereleaseIdentifier.value,
+            this.#prereleaseIdentifier.value,
             ...newPolicyVersion.prerelease.slice(1)
           ];
         } else {
           // Update 1.5.0 to 1.5.0-beta
           // Since there is no length, we can just set to a new array
-          newPolicyVersion.prerelease = [this._prereleaseIdentifier.value];
+          newPolicyVersion.prerelease = [this.#prereleaseIdentifier.value];
         }
         newVersion = newPolicyVersion.format();
       }
 
       if (newVersion) {
-        versionConfig.update(this._versionPolicy.value, newVersion, true);
+        versionConfig.update(this.#versionPolicy.value, newVersion, true);
       }
     } else {
       throw new Error(
@@ -195,12 +195,12 @@ export class VersionAction extends BaseRushAction {
     }
   }
 
-  private _validateInput(): void {
-    if (this._bumpVersion.value && this._ensureVersionPolicy.value) {
+  #validateInput(): void {
+    if (this.#bumpVersion.value && this.#ensureVersionPolicy.value) {
       throw new Error('Please choose --bump or --ensure-version-policy but not together.');
     }
 
-    if (this._overwriteBump.value && !Enum.tryGetValueByKey(BumpType, this._overwriteBump.value)) {
+    if (this.#overwriteBump.value && !Enum.tryGetValueByKey(BumpType, this.#overwriteBump.value)) {
       throw new Error(
         'The value of override-bump is not valid.  ' +
           'Valid values include prerelease, patch, preminor, minor, and major'
@@ -208,7 +208,7 @@ export class VersionAction extends BaseRushAction {
     }
   }
 
-  private _validateResult(variant: string | undefined): void {
+  #validateResult(variant: string | undefined): void {
     // Load the config from file to avoid using inconsistent in-memory data.
     const rushConfig: RushConfiguration = RushConfiguration.loadFromConfigurationFile(
       this.rushConfiguration.rushJsonFile
@@ -234,13 +234,13 @@ export class VersionAction extends BaseRushAction {
     }
   }
 
-  private async _gitProcessAsync(
+  async #gitProcessAsync(
     tempBranch: string,
     targetBranch: string | undefined,
     variant: string | undefined
   ): Promise<void> {
     // Validate the result before commit.
-    this._validateResult(variant);
+    this.#validateResult(variant);
 
     const git: Git = new Git(this.rushConfiguration);
     const publishGit: PublishGit = new PublishGit(git, targetBranch);
@@ -262,7 +262,7 @@ export class VersionAction extends BaseRushAction {
       await publishGit.addChangesAsync(':/**/CHANGELOG.md');
       await publishGit.commitAsync(
         this.rushConfiguration.gitChangeLogUpdateCommitMessage || DEFAULT_CHANGELOG_UPDATE_MESSAGE,
-        !this._ignoreGitHooksParameter.value
+        !this.#ignoreGitHooksParameter.value
       );
     }
 
@@ -276,25 +276,25 @@ export class VersionAction extends BaseRushAction {
       await publishGit.addChangesAsync(':/**/package.json');
       await publishGit.commitAsync(
         this.rushConfiguration.gitVersionBumpCommitMessage || DEFAULT_PACKAGE_UPDATE_MESSAGE,
-        !this._ignoreGitHooksParameter.value
+        !this.#ignoreGitHooksParameter.value
       );
     }
 
     if (changeLogUpdated || packageJsonUpdated) {
-      await publishGit.pushAsync(tempBranch, !this._ignoreGitHooksParameter.value, false);
+      await publishGit.pushAsync(tempBranch, !this.#ignoreGitHooksParameter.value, false);
 
       // Now merge to target branch.
       await publishGit.fetchAsync();
       await publishGit.checkoutAsync(targetBranch);
-      await publishGit.pullAsync(!this._ignoreGitHooksParameter.value);
-      await publishGit.mergeAsync(tempBranch, !this._ignoreGitHooksParameter.value);
-      await publishGit.pushAsync(targetBranch, !this._ignoreGitHooksParameter.value, false);
-      await publishGit.deleteBranchAsync(tempBranch, true, !this._ignoreGitHooksParameter.value);
+      await publishGit.pullAsync(!this.#ignoreGitHooksParameter.value);
+      await publishGit.mergeAsync(tempBranch, !this.#ignoreGitHooksParameter.value);
+      await publishGit.pushAsync(targetBranch, !this.#ignoreGitHooksParameter.value, false);
+      await publishGit.deleteBranchAsync(tempBranch, true, !this.#ignoreGitHooksParameter.value);
     } else {
       // skip commits
       await publishGit.fetchAsync();
       await publishGit.checkoutAsync(targetBranch);
-      await publishGit.deleteBranchAsync(tempBranch, false, !this._ignoreGitHooksParameter.value);
+      await publishGit.deleteBranchAsync(tempBranch, false, !this.#ignoreGitHooksParameter.value);
     }
   }
 }
diff --git a/libraries/rush-lib/src/cli/parsing/SelectionParameterSet.ts b/libraries/rush-lib/src/cli/parsing/SelectionParameterSet.ts
index 758fbb5737b..96f81580383 100644
--- a/libraries/rush-lib/src/cli/parsing/SelectionParameterSet.ts
+++ b/libraries/rush-lib/src/cli/parsing/SelectionParameterSet.ts
@@ -43,20 +43,20 @@ interface ISelectionParameterSetOptions {
  * It is a separate component such that unrelated actions can share the same parameters.
  */
 export class SelectionParameterSet {
-  private readonly _rushConfiguration: RushConfiguration;
+  readonly #rushConfiguration: RushConfiguration;
 
-  private readonly _fromProject: CommandLineStringListParameter;
-  private readonly _impactedByProject: CommandLineStringListParameter;
-  private readonly _impactedByExceptProject: CommandLineStringListParameter;
-  private readonly _onlyProject: CommandLineStringListParameter;
-  private readonly _toProject: CommandLineStringListParameter;
-  private readonly _toExceptProject: CommandLineStringListParameter;
-  private readonly _subspaceParameter: CommandLineStringParameter | undefined;
+  readonly #fromProject: CommandLineStringListParameter;
+  readonly #impactedByProject: CommandLineStringListParameter;
+  readonly #impactedByExceptProject: CommandLineStringListParameter;
+  readonly #onlyProject: CommandLineStringListParameter;
+  readonly #toProject: CommandLineStringListParameter;
+  readonly #toExceptProject: CommandLineStringListParameter;
+  readonly #subspaceParameter: CommandLineStringParameter | undefined;
 
-  private readonly _fromVersionPolicy: CommandLineStringListParameter;
-  private readonly _toVersionPolicy: CommandLineStringListParameter;
+  readonly #fromVersionPolicy: CommandLineStringListParameter;
+  readonly #toVersionPolicy: CommandLineStringListParameter;
 
-  private readonly _selectorParserByScope: Map<string, ISelectorParser<RushConfigurationProject>>;
+  readonly #selectorParserByScope: Map<string, ISelectorParser<RushConfigurationProject>>;
 
   public constructor(
     rushConfiguration: RushConfiguration,
@@ -64,7 +64,7 @@ export class SelectionParameterSet {
     options: ISelectionParameterSetOptions
   ) {
     const { gitOptions, includeSubspaceSelector, cwd } = options;
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
 
     const selectorParsers: Map<string, ISelectorParser<RushConfigurationProject>> = new Map<
       string,
@@ -79,7 +79,7 @@ export class SelectionParameterSet {
     selectorParsers.set('subspace', new SubspaceSelectorParser(rushConfiguration));
     selectorParsers.set('path', new PathProjectSelectorParser(rushConfiguration, cwd));
 
-    this._selectorParserByScope = selectorParsers;
+    this.#selectorParserByScope = selectorParsers;
 
     const getCompletionsAsync: () => Promise<string[]> = async (): Promise<string[]> => {
       const completions: string[] = ['.'];
@@ -97,7 +97,7 @@ export class SelectionParameterSet {
       return completions;
     };
 
-    this._toProject = action.defineStringListParameter({
+    this.#toProject = action.defineStringListParameter({
       parameterLongName: '--to',
       parameterShortName: '-t',
       argumentName: 'PROJECT',
@@ -109,7 +109,7 @@ export class SelectionParameterSet {
         ' For details, refer to the website article "Selecting subsets of projects".',
       getCompletionsAsync
     });
-    this._toExceptProject = action.defineStringListParameter({
+    this.#toExceptProject = action.defineStringListParameter({
       parameterLongName: '--to-except',
       parameterShortName: '-T',
       argumentName: 'PROJECT',
@@ -123,7 +123,7 @@ export class SelectionParameterSet {
       getCompletionsAsync
     });
 
-    this._fromProject = action.defineStringListParameter({
+    this.#fromProject = action.defineStringListParameter({
       parameterLongName: '--from',
       parameterShortName: '-f',
       argumentName: 'PROJECT',
@@ -136,7 +136,7 @@ export class SelectionParameterSet {
         ' For details, refer to the website article "Selecting subsets of projects".',
       getCompletionsAsync
     });
-    this._onlyProject = action.defineStringListParameter({
+    this.#onlyProject = action.defineStringListParameter({
       parameterLongName: '--only',
       parameterShortName: '-o',
       argumentName: 'PROJECT',
@@ -150,7 +150,7 @@ export class SelectionParameterSet {
       getCompletionsAsync
     });
 
-    this._impactedByProject = action.defineStringListParameter({
+    this.#impactedByProject = action.defineStringListParameter({
       parameterLongName: '--impacted-by',
       parameterShortName: '-i',
       argumentName: 'PROJECT',
@@ -165,7 +165,7 @@ export class SelectionParameterSet {
       getCompletionsAsync
     });
 
-    this._impactedByExceptProject = action.defineStringListParameter({
+    this.#impactedByExceptProject = action.defineStringListParameter({
       parameterLongName: '--impacted-by-except',
       parameterShortName: '-I',
       argumentName: 'PROJECT',
@@ -180,7 +180,7 @@ export class SelectionParameterSet {
       getCompletionsAsync
     });
 
-    this._toVersionPolicy = action.defineStringListParameter({
+    this.#toVersionPolicy = action.defineStringListParameter({
       parameterLongName: '--to-version-policy',
       argumentName: 'VERSION_POLICY_NAME',
       description:
@@ -190,7 +190,7 @@ export class SelectionParameterSet {
         ' belonging to VERSION_POLICY_NAME.' +
         ' For details, refer to the website article "Selecting subsets of projects".'
     });
-    this._fromVersionPolicy = action.defineStringListParameter({
+    this.#fromVersionPolicy = action.defineStringListParameter({
       parameterLongName: '--from-version-policy',
       argumentName: 'VERSION_POLICY_NAME',
       description:
@@ -202,7 +202,7 @@ export class SelectionParameterSet {
     });
 
     if (includeSubspaceSelector) {
-      this._subspaceParameter = action.defineStringParameter({
+      this.#subspaceParameter = action.defineStringParameter({
         parameterLongName: SUBSPACE_LONG_ARG_NAME,
         argumentName: 'SUBSPACE_NAME',
         description:
@@ -220,19 +220,19 @@ export class SelectionParameterSet {
    * such as `rush install --from thing-that-everything-depends-on`.
    */
   public didUserSelectAnything(): boolean {
-    if (this._subspaceParameter?.value) {
+    if (this.#subspaceParameter?.value) {
       return true;
     }
 
     return [
-      this._impactedByProject,
-      this._impactedByExceptProject,
-      this._onlyProject,
-      this._toProject,
-      this._fromProject,
-      this._toExceptProject,
-      this._fromVersionPolicy,
-      this._toVersionPolicy
+      this.#impactedByProject,
+      this.#impactedByExceptProject,
+      this.#onlyProject,
+      this.#toProject,
+      this.#fromProject,
+      this.#toExceptProject,
+      this.#fromVersionPolicy,
+      this.#toVersionPolicy
     ].some((x) => x.values.length > 0);
   }
 
@@ -246,30 +246,30 @@ export class SelectionParameterSet {
     allowEmptySelection?: boolean
   ): Promise<Set<RushConfigurationProject>> {
     // Hack out the old version-policy parameters
-    for (const value of this._fromVersionPolicy.values) {
-      (this._fromProject.values as string[]).push(`version-policy:${value}`);
+    for (const value of this.#fromVersionPolicy.values) {
+      (this.#fromProject.values as string[]).push(`version-policy:${value}`);
     }
-    for (const value of this._toVersionPolicy.values) {
-      (this._toProject.values as string[]).push(`version-policy:${value}`);
+    for (const value of this.#toVersionPolicy.values) {
+      (this.#toProject.values as string[]).push(`version-policy:${value}`);
     }
 
     const selectors: CommandLineStringListParameter[] = [
-      this._onlyProject,
-      this._fromProject,
-      this._toProject,
-      this._toExceptProject,
-      this._impactedByProject,
-      this._impactedByExceptProject
+      this.#onlyProject,
+      this.#fromProject,
+      this.#toProject,
+      this.#toExceptProject,
+      this.#impactedByProject,
+      this.#impactedByExceptProject
     ];
 
     // Check if any of the selection parameters have a value specified on the command line
     const isSelectionSpecified: boolean =
       selectors.some((param: CommandLineStringListParameter) => param.values.length > 0) ||
-      !!this._subspaceParameter?.value;
+      !!this.#subspaceParameter?.value;
 
     // If no selection parameters are specified, return everything
     if (!isSelectionSpecified) {
-      return allowEmptySelection ? new Set() : new Set(this._rushConfiguration.projects);
+      return allowEmptySelection ? new Set() : new Set(this.#rushConfiguration.projects);
     }
 
     const [
@@ -287,14 +287,14 @@ export class SelectionParameterSet {
       impactedByExceptProjects
     ] = await Promise.all(
       selectors.map((param: CommandLineStringListParameter) => {
-        return this._evaluateProjectParameterAsync(param, terminal);
+        return this.#evaluateProjectParameterAsync(param, terminal);
       })
     );
 
     let subspaceProjects: Iterable<RushConfigurationProject> = [];
 
-    if (this._subspaceParameter?.value) {
-      if (!this._rushConfiguration.subspacesFeatureEnabled) {
+    if (this.#subspaceParameter?.value) {
+      if (!this.#rushConfiguration.subspacesFeatureEnabled) {
         // eslint-disable-next-line no-console
         console.log();
         // eslint-disable-next-line no-console
@@ -307,7 +307,7 @@ export class SelectionParameterSet {
         throw new AlreadyReportedError();
       }
 
-      const subspace: Subspace = this._rushConfiguration.getSubspace(this._subspaceParameter.value);
+      const subspace: Subspace = this.#rushConfiguration.getSubspace(this.#subspaceParameter.value);
       subspaceProjects = subspace.getProjects();
     }
 
@@ -352,20 +352,20 @@ export class SelectionParameterSet {
     const args: string[] = [];
 
     // Include exactly these projects (--only)
-    for (const project of await this._evaluateProjectParameterAsync(this._onlyProject, terminal)) {
+    for (const project of await this.#evaluateProjectParameterAsync(this.#onlyProject, terminal)) {
       args.push(project.packageName);
     }
 
     // Include all projects that depend on these projects, and all dependencies thereof
     const fromProjects: Set<RushConfigurationProject> = Selection.union(
       // --from
-      await this._evaluateProjectParameterAsync(this._fromProject, terminal)
+      await this.#evaluateProjectParameterAsync(this.#fromProject, terminal)
     );
 
     // All specified projects and all projects that they depend on
     for (const project of Selection.union(
       // --to
-      await this._evaluateProjectParameterAsync(this._toProject, terminal),
+      await this.#evaluateProjectParameterAsync(this.#toProject, terminal),
       // --from / --from-version-policy
       Selection.expandAllConsumers(fromProjects)
     )) {
@@ -374,20 +374,20 @@ export class SelectionParameterSet {
 
     // --to-except
     // All projects that the project directly or indirectly declares as a dependency
-    for (const project of await this._evaluateProjectParameterAsync(this._toExceptProject, terminal)) {
+    for (const project of await this.#evaluateProjectParameterAsync(this.#toExceptProject, terminal)) {
       args.push(`${project.packageName}^...`);
     }
 
     // --impacted-by
     // The project and all projects directly or indirectly declare it as a dependency
-    for (const project of await this._evaluateProjectParameterAsync(this._impactedByProject, terminal)) {
+    for (const project of await this.#evaluateProjectParameterAsync(this.#impactedByProject, terminal)) {
       args.push(`...${project.packageName}`);
     }
 
     // --impacted-by-except
     // All projects that directly or indirectly declare the specified project as a dependency
-    for (const project of await this._evaluateProjectParameterAsync(
-      this._impactedByExceptProject,
+    for (const project of await this.#evaluateProjectParameterAsync(
+      this.#impactedByExceptProject,
       terminal
     )) {
       args.push(`...^${project.packageName}`);
@@ -401,15 +401,15 @@ export class SelectionParameterSet {
    */
   public getTelemetry(): { [key: string]: string } {
     return {
-      command_from: `${this._fromProject.values.length > 0}`,
-      command_impactedBy: `${this._impactedByProject.values.length > 0}`,
-      command_impactedByExcept: `${this._impactedByExceptProject.values.length > 0}`,
-      command_only: `${this._onlyProject.values.length > 0}`,
-      command_to: `${this._toProject.values.length > 0}`,
-      command_toExcept: `${this._toExceptProject.values.length > 0}`,
-
-      command_fromVersionPolicy: `${this._fromVersionPolicy.values.length > 0}`,
-      command_toVersionPolicy: `${this._toVersionPolicy.values.length > 0}`
+      command_from: `${this.#fromProject.values.length > 0}`,
+      command_impactedBy: `${this.#impactedByProject.values.length > 0}`,
+      command_impactedByExcept: `${this.#impactedByExceptProject.values.length > 0}`,
+      command_only: `${this.#onlyProject.values.length > 0}`,
+      command_to: `${this.#toProject.values.length > 0}`,
+      command_toExcept: `${this.#toExceptProject.values.length > 0}`,
+
+      command_fromVersionPolicy: `${this.#fromVersionPolicy.values.length > 0}`,
+      command_toVersionPolicy: `${this.#toVersionPolicy.values.length > 0}`
     };
   }
 
@@ -417,7 +417,7 @@ export class SelectionParameterSet {
    * Computes the referents of parameters that accept a project identifier.
    * Handles '.', unscoped names, and scoped names.
    */
-  private async _evaluateProjectParameterAsync(
+  async #evaluateProjectParameterAsync(
     listParameter: CommandLineStringListParameter,
     terminal: ITerminal
   ): Promise<Set<RushConfigurationProject>> {
@@ -456,12 +456,12 @@ export class SelectionParameterSet {
       }
 
       const handler: ISelectorParser<RushConfigurationProject> | undefined =
-        this._selectorParserByScope.get(scope);
+        this.#selectorParserByScope.get(scope);
       if (!handler) {
         terminal.writeErrorLine(
           `Unsupported selector prefix "${scope}" passed to "${parameterName}": "${rawSelector}".` +
             ` Supported prefixes: ${Array.from(
-              this._selectorParserByScope.keys(),
+              this.#selectorParserByScope.keys(),
               (selectorParserScope: string) => `"${selectorParserScope}:"`
             ).join(', ')}`
         );
diff --git a/libraries/rush-lib/src/cli/scriptActions/GlobalScriptAction.ts b/libraries/rush-lib/src/cli/scriptActions/GlobalScriptAction.ts
index 231508a66c7..421bd5adeaf 100644
--- a/libraries/rush-lib/src/cli/scriptActions/GlobalScriptAction.ts
+++ b/libraries/rush-lib/src/cli/scriptActions/GlobalScriptAction.ts
@@ -43,40 +43,40 @@ export interface IGlobalScriptActionOptions extends IBaseScriptActionOptions<IGl
  * invoke scripts from package.json in the same way as a custom command.
  */
 export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
-  private readonly _shellCommand: string;
-  private readonly _autoinstallerName: string;
-  private readonly _autoinstallerFullPath: string;
-  private readonly _providedByPlugin: boolean;
+  readonly #shellCommand: string;
+  readonly #autoinstallerName: string;
+  readonly #autoinstallerFullPath: string;
+  readonly #providedByPlugin: boolean;
 
-  private _customParametersByLongName: ReadonlyMap<string, CommandLineParameter> | undefined;
-  private _isHandled: boolean = false;
+  #customParametersByLongName: ReadonlyMap<string, CommandLineParameter> | undefined;
+  #isHandled: boolean = false;
 
   public constructor(options: IGlobalScriptActionOptions) {
     super(options);
     const { shellCommand, providedByPlugin, autoinstallerName = '' } = options;
-    this._shellCommand = shellCommand;
-    this._providedByPlugin = providedByPlugin;
-    this._autoinstallerName = autoinstallerName;
+    this.#shellCommand = shellCommand;
+    this.#providedByPlugin = providedByPlugin;
+    this.#autoinstallerName = autoinstallerName;
 
-    if (this._autoinstallerName) {
-      Autoinstaller.validateName(this._autoinstallerName);
+    if (this.#autoinstallerName) {
+      Autoinstaller.validateName(this.#autoinstallerName);
 
       // Example: .../common/autoinstallers/my-task
-      this._autoinstallerFullPath = path.join(
+      this.#autoinstallerFullPath = path.join(
         this.rushConfiguration.commonAutoinstallersFolder,
-        this._autoinstallerName
+        this.#autoinstallerName
       );
 
-      if (!FileSystem.exists(this._autoinstallerFullPath)) {
+      if (!FileSystem.exists(this.#autoinstallerFullPath)) {
         throw new Error(
           `The custom command "${this.actionName}" specifies an "autoinstallerName" setting` +
             ' but the path does not exist: ' +
-            this._autoinstallerFullPath
+            this.#autoinstallerFullPath
         );
       }
 
       // Example: .../common/autoinstallers/my-task/package.json
-      const packageJsonPath: string = path.join(this._autoinstallerFullPath, 'package.json');
+      const packageJsonPath: string = path.join(this.#autoinstallerFullPath, 'package.json');
       if (!FileSystem.exists(packageJsonPath)) {
         throw new Error(
           `The custom command "${this.actionName}" specifies an "autoinstallerName" setting` +
@@ -87,15 +87,15 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
 
       const packageJson: IPackageJson = JsonFile.load(packageJsonPath);
 
-      if (packageJson.name !== this._autoinstallerName) {
+      if (packageJson.name !== this.#autoinstallerName) {
         throw new Error(
           `The custom command "${this.actionName}" specifies an "autoinstallerName" setting,` +
-            ` but the package.json file's "name" field is not "${this._autoinstallerName}": ` +
+            ` but the package.json file's "name" field is not "${this.#autoinstallerName}": ` +
             packageJsonPath
         );
       }
     } else {
-      this._autoinstallerFullPath = '';
+      this.#autoinstallerFullPath = '';
     }
 
     this.defineScriptParameters();
@@ -105,7 +105,7 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
    * {@inheritDoc IGlobalCommand.setHandled}
    */
   public setHandled(): void {
-    this._isHandled = true;
+    this.#isHandled = true;
   }
 
   /**
@@ -114,15 +114,15 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
   public getCustomParametersByLongName<TParameter extends CommandLineParameter>(
     longName: string
   ): TParameter {
-    if (!this._customParametersByLongName) {
+    if (!this.#customParametersByLongName) {
       const map: Map<string, CommandLineParameter> = new Map();
       for (const [parameterJson, parameter] of this.customParameters) {
         map.set(parameterJson.longName, parameter);
       }
-      this._customParametersByLongName = map;
+      this.#customParametersByLongName = map;
     }
 
-    const parameter: CommandLineParameter | undefined = this._customParametersByLongName.get(longName);
+    const parameter: CommandLineParameter | undefined = this.#customParametersByLongName.get(longName);
     if (!parameter) {
       throw new Error(
         `The command "${this.actionName}" does not have a custom parameter with long name "${longName}".`
@@ -132,9 +132,9 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
     return parameter as TParameter;
   }
 
-  private async _prepareAutoinstallerNameAsync(): Promise<void> {
+  async #prepareAutoinstallerNameAsync(): Promise<void> {
     const autoInstaller: Autoinstaller = new Autoinstaller({
-      autoinstallerName: this._autoinstallerName,
+      autoinstallerName: this.#autoinstallerName,
       rushConfiguration: this.rushConfiguration,
       rushGlobalFolder: this.rushGlobalFolder
     });
@@ -158,11 +158,11 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
 
     // If a plugin hook called setHandled(), the command has been fully handled.
     // Skip the default shell command execution.
-    if (this._isHandled) {
+    if (this.#isHandled) {
       return;
     }
 
-    if (this._providedByPlugin) {
+    if (this.#providedByPlugin) {
       throw new Error(
         `The custom command "${this.actionName}" is a "${RushConstants.globalPluginCommandKind}" command, ` +
           'meaning its implementation must be provided entirely by a Rush plugin. However, no plugin ' +
@@ -171,7 +171,7 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
       );
     }
 
-    if (this._shellCommand === '') {
+    if (this.#shellCommand === '') {
       throw new Error(
         `The custom command "${this.actionName}" has an empty "shellCommand" value, but no plugin ` +
           'called setHandled() for this command. An empty "shellCommand" is intended for global ' +
@@ -182,12 +182,12 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
     const additionalPathFolders: string[] =
       this.commandLineConfiguration?.additionalPathFolders.slice() || [];
 
-    if (this._autoinstallerName) {
+    if (this.#autoinstallerName) {
       await measureAsyncFn('rush:globalScriptAction:prepareAutoinstaller', () =>
-        this._prepareAutoinstallerNameAsync()
+        this.#prepareAutoinstallerNameAsync()
       );
 
-      const autoinstallerNameBinPath: string = path.join(this._autoinstallerFullPath, 'node_modules', '.bin');
+      const autoinstallerNameBinPath: string = path.join(this.#autoinstallerFullPath, 'node_modules', '.bin');
       additionalPathFolders.push(autoinstallerNameBinPath);
     }
 
@@ -208,7 +208,7 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
       customParameterValues[i] = customParameterValue;
     }
 
-    let shellCommand: string = this._shellCommand;
+    let shellCommand: string = this.#shellCommand;
     if (customParameterValues.length > 0) {
       shellCommand += ' ' + customParameterValues.join(' ');
     }
@@ -216,9 +216,9 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
     const shellCommandTokenContext: IShellCommandTokenContext | undefined =
       this.commandLineConfiguration?.shellCommandTokenContext;
     if (shellCommandTokenContext) {
-      shellCommand = this._expandShellCommandWithTokens(shellCommand, shellCommandTokenContext);
+      shellCommand = this.#expandShellCommandWithTokens(shellCommand, shellCommandTokenContext);
     }
-    this._rejectAnyTokensInShellCommand(shellCommand, shellCommandTokenContext);
+    this.#rejectAnyTokensInShellCommand(shellCommand, shellCommandTokenContext);
 
     const stopwatch: Stopwatch = Stopwatch.start();
 
@@ -257,7 +257,7 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
     }
   }
 
-  private _expandShellCommandWithTokens(
+  #expandShellCommandWithTokens(
     shellCommand: string,
     tokenContext: IShellCommandTokenContext
   ): string {
@@ -268,7 +268,7 @@ export class GlobalScriptAction extends BaseScriptAction<IGlobalCommandConfig> {
     return expandedShellCommand;
   }
 
-  private _rejectAnyTokensInShellCommand(
+  #rejectAnyTokensInShellCommand(
     shellCommand: string,
     tokenContext?: IShellCommandTokenContext
   ): void {
diff --git a/libraries/rush-lib/src/cli/scriptActions/PhasedScriptAction.ts b/libraries/rush-lib/src/cli/scriptActions/PhasedScriptAction.ts
index 7b79e36e081..dd3378cdac0 100644
--- a/libraries/rush-lib/src/cli/scriptActions/PhasedScriptAction.ts
+++ b/libraries/rush-lib/src/cli/scriptActions/PhasedScriptAction.ts
@@ -132,33 +132,33 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
   public readonly hooks: PhasedCommandHooks;
   public readonly sessionAbortController: AbortController;
 
-  private readonly _enableParallelism: boolean;
-  private readonly _allowOversubscription: boolean;
-  private readonly _isIncrementalBuildAllowed: boolean;
-  private readonly _disableBuildCache: boolean;
-  private readonly _originalPhases: ReadonlySet<IPhase>;
-  private readonly _initialPhases: ReadonlySet<IPhase>;
-  private readonly _watchPhases: ReadonlySet<IPhase>;
-  private readonly _watchDebounceMs: number;
-  private readonly _alwaysWatch: boolean;
-  private readonly _alwaysInstall: boolean | undefined;
-  private readonly _includeAllProjectsInWatchGraph: boolean;
-  private readonly _terminal: ITerminal;
-
-  private readonly _changedProjectsOnlyParameter: CommandLineFlagParameter | undefined;
-  private readonly _selectionParameters: SelectionParameterSet;
-  private readonly _verboseParameter: CommandLineFlagParameter;
-  private readonly _parallelismParameter: CommandLineStringParameter | undefined;
-  private readonly _ignoreHooksParameter: CommandLineFlagParameter;
-  private readonly _watchParameter: CommandLineFlagParameter | undefined;
-  private readonly _timelineParameter: CommandLineFlagParameter | undefined;
-  private readonly _cobuildPlanParameter: CommandLineFlagParameter | undefined;
-  private readonly _installParameter: CommandLineFlagParameter | undefined;
-  private readonly _variantParameter: CommandLineStringParameter | undefined;
-  private readonly _noIPCParameter: CommandLineFlagParameter | undefined;
-  private readonly _nodeDiagnosticDirParameter: CommandLineStringParameter;
-  private readonly _debugBuildCacheIdsParameter: CommandLineFlagParameter;
-  private readonly _includePhaseDeps: CommandLineFlagParameter | undefined;
+  readonly #enableParallelism: boolean;
+  readonly #allowOversubscription: boolean;
+  readonly #isIncrementalBuildAllowed: boolean;
+  readonly #disableBuildCache: boolean;
+  readonly #originalPhases: ReadonlySet<IPhase>;
+  readonly #initialPhases: ReadonlySet<IPhase>;
+  readonly #watchPhases: ReadonlySet<IPhase>;
+  readonly #watchDebounceMs: number;
+  readonly #alwaysWatch: boolean;
+  readonly #alwaysInstall: boolean | undefined;
+  readonly #includeAllProjectsInWatchGraph: boolean;
+  readonly #terminal: ITerminal;
+
+  readonly #changedProjectsOnlyParameter: CommandLineFlagParameter | undefined;
+  readonly #selectionParameters: SelectionParameterSet;
+  readonly #verboseParameter: CommandLineFlagParameter;
+  readonly #parallelismParameter: CommandLineStringParameter | undefined;
+  readonly #ignoreHooksParameter: CommandLineFlagParameter;
+  readonly #watchParameter: CommandLineFlagParameter | undefined;
+  readonly #timelineParameter: CommandLineFlagParameter | undefined;
+  readonly #cobuildPlanParameter: CommandLineFlagParameter | undefined;
+  readonly #installParameter: CommandLineFlagParameter | undefined;
+  readonly #variantParameter: CommandLineStringParameter | undefined;
+  readonly #noIPCParameter: CommandLineFlagParameter | undefined;
+  readonly #nodeDiagnosticDirParameter: CommandLineStringParameter;
+  readonly #debugBuildCacheIdsParameter: CommandLineFlagParameter;
+  readonly #includePhaseDeps: CommandLineFlagParameter | undefined;
 
   public constructor(options: IPhasedScriptActionOptions) {
     super(options);
@@ -176,25 +176,25 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       includeAllProjectsInWatchGraph,
       phases
     } = options;
-    this._enableParallelism = enableParallelism;
-    this._allowOversubscription = allowOversubscription;
-    this._isIncrementalBuildAllowed = incremental;
-    this._disableBuildCache = disableBuildCache;
-    this._originalPhases = originalPhases;
-    this._initialPhases = initialPhases;
-    this._watchPhases = watchPhases;
-    this._watchDebounceMs = watchDebounceMs;
-    this._alwaysWatch = alwaysWatch;
-    this._alwaysInstall = alwaysInstall;
-    this._includeAllProjectsInWatchGraph = includeAllProjectsInWatchGraph;
+    this.#enableParallelism = enableParallelism;
+    this.#allowOversubscription = allowOversubscription;
+    this.#isIncrementalBuildAllowed = incremental;
+    this.#disableBuildCache = disableBuildCache;
+    this.#originalPhases = originalPhases;
+    this.#initialPhases = initialPhases;
+    this.#watchPhases = watchPhases;
+    this.#watchDebounceMs = watchDebounceMs;
+    this.#alwaysWatch = alwaysWatch;
+    this.#alwaysInstall = alwaysInstall;
+    this.#includeAllProjectsInWatchGraph = includeAllProjectsInWatchGraph;
     this._runsBeforeInstall = false;
     this.sessionAbortController = new AbortController();
 
     this.hooks = new PhasedCommandHooks();
 
-    this._terminal = new Terminal(this.rushSession.terminalProvider);
+    this.#terminal = new Terminal(this.rushSession.terminalProvider);
 
-    this._parallelismParameter = this._enableParallelism
+    this.#parallelismParameter = this.#enableParallelism
       ? this.defineStringParameter({
           parameterLongName: '--parallelism',
           parameterShortName: '-p',
@@ -208,20 +208,20 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         })
       : undefined;
 
-    this._timelineParameter = this.defineFlagParameter({
+    this.#timelineParameter = this.defineFlagParameter({
       parameterLongName: '--timeline',
       description:
         'After the build is complete, print additional statistics and CPU usage information,' +
         ' including an ASCII chart of the start and stop times for each operation.'
     });
-    this._cobuildPlanParameter = this.defineFlagParameter({
+    this.#cobuildPlanParameter = this.defineFlagParameter({
       parameterLongName: '--log-cobuild-plan',
       description:
         '(EXPERIMENTAL) Before the build starts, log information about the cobuild state. This will include information about ' +
         'clusters and the projects that are part of each cluster.'
     });
 
-    this._selectionParameters = new SelectionParameterSet(this.rushConfiguration, this, {
+    this.#selectionParameters = new SelectionParameterSet(this.rushConfiguration, this, {
       gitOptions: {
         // Include lockfile processing since this expands the selection, and we need to select
         // at least the same projects selected with the same query to "rush build"
@@ -233,13 +233,13 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       cwd: this.parser.cwd
     });
 
-    this._verboseParameter = this.defineFlagParameter({
+    this.#verboseParameter = this.defineFlagParameter({
       parameterLongName: '--verbose',
       parameterShortName: '-v',
       description: 'Display the logs during the build, rather than just displaying the build status summary'
     });
 
-    this._includePhaseDeps = this.defineFlagParameter({
+    this.#includePhaseDeps = this.defineFlagParameter({
       parameterLongName: '--include-phase-deps',
       description:
         'If the selected projects are "unsafe" (missing some dependencies), add the minimal set of phase dependencies. For example, ' +
@@ -247,7 +247,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         `Using "--impacted-by A --include-phase-deps" avoids that work by performing "_phase:test" only for downstream projects.`
     });
 
-    this._changedProjectsOnlyParameter = this._isIncrementalBuildAllowed
+    this.#changedProjectsOnlyParameter = this.#isIncrementalBuildAllowed
       ? this.defineFlagParameter({
           parameterLongName: '--changed-projects-only',
           parameterShortName: '-c',
@@ -260,7 +260,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         })
       : undefined;
 
-    this._ignoreHooksParameter = this.defineFlagParameter({
+    this.#ignoreHooksParameter = this.defineFlagParameter({
       parameterLongName: '--ignore-hooks',
       description:
         `Skips execution of the "eventHooks" scripts defined in ${RushConstants.rushJsonFilename}. ` +
@@ -268,12 +268,12 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
     });
 
     // Only define the parameter if it has an effect.
-    this._watchParameter =
-      this._watchPhases.size > 0 && !this._alwaysWatch
+    this.#watchParameter =
+      this.#watchPhases.size > 0 && !this.#alwaysWatch
         ? this.defineFlagParameter({
             parameterLongName: '--watch',
             description: `Starts a file watcher after initial execution finishes. Will run the following phases on affected projects: ${Array.from(
-              this._watchPhases,
+              this.#watchPhases,
               (phase: IPhase) => phase.name
             ).join(', ')}`
           })
@@ -281,8 +281,8 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
 
     // If `this._alwaysInstall === undefined`, Rush does not define the parameter
     // but a repository may still define a custom parameter with the same name.
-    this._installParameter =
-      this._alwaysInstall === false
+    this.#installParameter =
+      this.#alwaysInstall === false
         ? this.defineFlagParameter({
             parameterLongName: '--install',
             description:
@@ -291,13 +291,13 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
           })
         : undefined;
 
-    this._variantParameter =
-      this._alwaysInstall !== undefined ? this.defineStringParameter(VARIANT_PARAMETER) : undefined;
+    this.#variantParameter =
+      this.#alwaysInstall !== undefined ? this.defineStringParameter(VARIANT_PARAMETER) : undefined;
 
     const isIpcSupported: boolean =
-      this._watchPhases.size > 0 &&
+      this.#watchPhases.size > 0 &&
       !!this.rushConfiguration.experimentsConfiguration.configuration.useIPCScriptsInWatchMode;
-    this._noIPCParameter = isIpcSupported
+    this.#noIPCParameter = isIpcSupported
       ? this.defineFlagParameter({
           parameterLongName: '--no-ipc',
           description:
@@ -306,7 +306,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         })
       : undefined;
 
-    this._nodeDiagnosticDirParameter = this.defineStringParameter({
+    this.#nodeDiagnosticDirParameter = this.defineStringParameter({
       parameterLongName: '--node-diagnostic-dir',
       argumentName: 'DIRECTORY',
       description:
@@ -314,7 +314,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         'This directory will contain a subdirectory for each project and phase.'
     });
 
-    this._debugBuildCacheIdsParameter = this.defineFlagParameter({
+    this.#debugBuildCacheIdsParameter = this.defineFlagParameter({
       parameterLongName: '--debug-build-cache-ids',
       description:
         'Logs information about the components of the build cache ids for individual operations. This is useful for debugging the incremental build logic.'
@@ -335,7 +335,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       subspacesFeatureEnabled,
       pnpmOptions: { useWorkspaces }
     } = this.rushConfiguration;
-    if (this._alwaysInstall || this._installParameter?.value) {
+    if (this.#alwaysInstall || this.#installParameter?.value) {
       await measureAsyncFn(`${PERF_PREFIX}:install`, async () => {
         const { doBasicInstallAsync } = await import(
           /* webpackChunkName: 'doBasicInstallAsync' */
@@ -343,12 +343,12 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         );
 
         const variant: string | undefined = await getVariantAsync(
-          this._variantParameter,
+          this.#variantParameter,
           this.rushConfiguration,
           true
         );
         await doBasicInstallAsync({
-          terminal: this._terminal,
+          terminal: this.#terminal,
           rushConfiguration: this.rushConfiguration,
           rushGlobalFolder: this.rushGlobalFolder,
           isDebug: this.parser.isDebug,
@@ -382,16 +382,16 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       });
     }
 
-    measureFn(`${PERF_PREFIX}:doBeforeTask`, () => this._doBeforeTask());
+    measureFn(`${PERF_PREFIX}:doBeforeTask`, () => this.#doBeforeTask());
 
     const hooks: PhasedCommandHooks = this.hooks;
-    const terminal: ITerminal = this._terminal;
+    const terminal: ITerminal = this.#terminal;
 
     // if this is parallelizable, then use the value from the flag (undefined or a number),
     // if parallelism is not enabled, then restrict to 1 core
     const maxParallelism: number = getNumberOfCores();
-    const parallelism: Parallelism = this._enableParallelism
-      ? parseParallelism(this._parallelismParameter?.value)
+    const parallelism: Parallelism = this.#enableParallelism
+      ? parseParallelism(this.#parallelismParameter?.value)
       : 1;
 
     await measureAsyncFn(`${PERF_PREFIX}:applyStandardPlugins`, async () => {
@@ -407,7 +407,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       // Forward ignored parameters to child processes as an environment variable
       new IgnoredParametersPlugin().apply(hooks);
 
-      const showTimeline: boolean = this._timelineParameter?.value ?? false;
+      const showTimeline: boolean = this.#timelineParameter?.value ?? false;
       if (showTimeline) {
         const { ConsoleTimelinePlugin } = await import(
           /* webpackChunkName: 'ConsoleTimelinePlugin' */
@@ -416,7 +416,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         new ConsoleTimelinePlugin(terminal).apply(this.hooks);
       }
 
-      const diagnosticDir: string | undefined = this._nodeDiagnosticDirParameter.value;
+      const diagnosticDir: string | undefined = this.#nodeDiagnosticDirParameter.value;
       if (diagnosticDir) {
         new NodeDiagnosticDirPlugin({
           diagnosticDir
@@ -446,13 +446,13 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       });
     }
 
-    const isQuietMode: boolean = !this._verboseParameter.value;
+    const isQuietMode: boolean = !this.#verboseParameter.value;
 
-    const changedProjectsOnly: boolean = !!this._changedProjectsOnlyParameter?.value;
+    const changedProjectsOnly: boolean = !!this.#changedProjectsOnlyParameter?.value;
 
     let buildCacheConfiguration: BuildCacheConfiguration | undefined;
     let cobuildConfiguration: CobuildConfiguration | undefined;
-    if (!this._disableBuildCache) {
+    if (!this.#disableBuildCache) {
       await measureAsyncFn(`${PERF_PREFIX}:configureBuildCache`, async () => {
         [buildCacheConfiguration, cobuildConfiguration] = await Promise.all([
           BuildCacheConfiguration.tryLoadAsync(terminal, this.rushConfiguration, this.rushSession),
@@ -468,13 +468,13 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       });
     }
 
-    const isWatch: boolean = this._watchParameter?.value || this._alwaysWatch;
-    const generateFullGraph: boolean = isWatch && this._includeAllProjectsInWatchGraph;
+    const isWatch: boolean = this.#watchParameter?.value || this.#alwaysWatch;
+    const generateFullGraph: boolean = isWatch && this.#includeAllProjectsInWatchGraph;
 
     try {
       const projectSelection: Set<RushConfigurationProject> = await measureAsyncFn(
         `${PERF_PREFIX}:getSelectedProjects`,
-        () => this._selectionParameters.getSelectedProjectsAsync(terminal, generateFullGraph)
+        () => this.#selectionParameters.getSelectedProjectsAsync(terminal, generateFullGraph)
       );
 
       const customParametersByName: Map<string, CommandLineParameter> = new Map();
@@ -490,7 +490,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       }
 
       await measureAsyncFn(`${PERF_PREFIX}:applySituationalPlugins`, async () => {
-        if (isWatch && this._noIPCParameter?.value === false) {
+        if (isWatch && this.#noIPCParameter?.value === false) {
           new (
             await import(
               /* webpackChunkName: 'IPCOperationRunnerPlugin' */ '../../logic/operations/IPCOperationRunnerPlugin'
@@ -521,23 +521,23 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
             useDirectFileTransfersForBuildCache
           }).apply(this.hooks);
 
-          if (this._debugBuildCacheIdsParameter.value) {
+          if (this.#debugBuildCacheIdsParameter.value) {
             new DebugHashesPlugin(terminal).apply(this.hooks);
           }
-        } else if (!this._disableBuildCache) {
+        } else if (!this.#disableBuildCache) {
           terminal.writeVerboseLine(`Incremental strategy: output preservation`);
           // Explicitly disabling the build cache also disables legacy skip detection.
           new LegacySkipPlugin({
             allowWarningsInSuccessfulBuild: buildSkipWithAllowWarningsInSuccessfulBuild,
             terminal,
             changedProjectsOnly,
-            isIncrementalBuildAllowed: this._isIncrementalBuildAllowed
+            isIncrementalBuildAllowed: this.#isIncrementalBuildAllowed
           }).apply(this.hooks);
         } else {
           terminal.writeVerboseLine(`Incremental strategy: none (full rebuild)`);
         }
 
-        const showBuildPlan: boolean = this._cobuildPlanParameter?.value ?? false;
+        const showBuildPlan: boolean = this.#cobuildPlanParameter?.value ?? false;
 
         if (showBuildPlan) {
           if (!buildCacheConfiguration?.buildCacheEnabled) {
@@ -567,7 +567,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
             RushProjectConfiguration.tryLoadForProjectsAsync(relevantProjects, terminal)
           );
 
-      const includePhaseDeps: boolean = this._includePhaseDeps?.value ?? false;
+      const includePhaseDeps: boolean = this.#includePhaseDeps?.value ?? false;
 
       const createOperationsContext: ICreateOperationsContext = {
         buildCacheConfiguration,
@@ -575,15 +575,15 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         customParameters: customParametersByName,
         changedProjectsOnly,
         includePhaseDeps,
-        isIncrementalBuildAllowed: this._isIncrementalBuildAllowed,
+        isIncrementalBuildAllowed: this.#isIncrementalBuildAllowed,
         isWatch,
         rushConfiguration: this.rushConfiguration,
         parallelism,
         phaseSelection: isWatch
-          ? this._watchPhases
+          ? this.#watchPhases
           : includePhaseDeps
-            ? this._originalPhases
-            : this._initialPhases,
+            ? this.#originalPhases
+            : this.#initialPhases,
         projectSelection,
         generateFullGraph,
         projectConfigurations
@@ -622,13 +622,14 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       let executionTelemetryHandler: IOperationGraphTelemetry | undefined;
       const { telemetry: parserTelemetry } = this.parser;
       if (parserTelemetry) {
-        const { _changedProjectsOnlyParameter: changedProjectsOnlyParameter } = this;
+        const changedProjectsOnlyParameter: CommandLineFlagParameter | undefined =
+          this.#changedProjectsOnlyParameter;
         executionTelemetryHandler = {
           changedProjectsOnlyKey:
             changedProjectsOnlyParameter?.scopedLongName ?? changedProjectsOnlyParameter?.longName,
           initialExtraData: {
             // Fields preserved across the command invocation
-            ...this._selectionParameters.getTelemetry(),
+            ...this.#selectionParameters.getTelemetry(),
             ...this.getParameterStringMap()
           },
           nameForLog: this.actionName,
@@ -645,7 +646,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
         destinations: [StdioWritable.instance],
         parallelism,
         maxParallelism,
-        allowOversubscription: this._allowOversubscription,
+        allowOversubscription: this.#allowOversubscription,
         isWatch,
         pauseNextIteration: false,
         getInputsSnapshotAsync,
@@ -671,7 +672,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
 
       const executeOptions: IExecuteOperationsOptions = {
         graph,
-        ignoreHooks: !!this._ignoreHooksParameter.value,
+        ignoreHooks: !!this.#ignoreHooksParameter.value,
         isWatch,
         stopwatch,
         terminal
@@ -700,7 +701,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
           graph,
           initialSnapshot,
           terminal,
-          debounceMs: this._watchDebounceMs
+          debounceMs: this.#watchDebounceMs
         });
         watcher.clearStatus();
 
@@ -714,7 +715,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       } else {
         await measureAsyncFn(`${PERF_PREFIX}:runInitialPhases`, () =>
           measureAsyncFn(`${PERF_PREFIX}:executeOperations`, () =>
-            this._executeOperationsAsync(executeOptions, initialIterationOptions)
+            this.#executeOperationsAsync(executeOptions, initialIterationOptions)
           )
         );
       }
@@ -728,7 +729,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
   /**
    * Runs a set of operations and reports the results.
    */
-  private async _executeOperationsAsync(
+  async #executeOperationsAsync(
     options: IExecuteOperationsOptions,
     iterationOptions: IOperationGraphIterationOptions
   ): Promise<void> {
@@ -773,7 +774,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
     }
 
     if (!ignoreHooks) {
-      measureFn(`${PERF_PREFIX}:doAfterTask`, () => this._doAfterTask());
+      measureFn(`${PERF_PREFIX}:doAfterTask`, () => this.#doAfterTask());
     }
 
     if (!success) {
@@ -781,7 +782,7 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
     }
   }
 
-  private _doBeforeTask(): void {
+  #doBeforeTask(): void {
     if (
       this.actionName !== RushConstants.buildCommandName &&
       this.actionName !== RushConstants.rebuildCommandName
@@ -792,10 +793,10 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
 
     SetupChecks.validate(this.rushConfiguration);
 
-    this.eventHooksManager.handle(Event.preRushBuild, this.parser.isDebug, this._ignoreHooksParameter.value);
+    this.eventHooksManager.handle(Event.preRushBuild, this.parser.isDebug, this.#ignoreHooksParameter.value);
   }
 
-  private _doAfterTask(): void {
+  #doAfterTask(): void {
     if (
       this.actionName !== RushConstants.buildCommandName &&
       this.actionName !== RushConstants.rebuildCommandName
@@ -803,6 +804,6 @@ export class PhasedScriptAction extends BaseScriptAction<IPhasedCommandConfig> i
       // Only collects information for built-in commands like build or rebuild.
       return;
     }
-    this.eventHooksManager.handle(Event.postRushBuild, this.parser.isDebug, this._ignoreHooksParameter.value);
+    this.eventHooksManager.handle(Event.postRushBuild, this.parser.isDebug, this.#ignoreHooksParameter.value);
   }
 }
diff --git a/libraries/rush-lib/src/logic/ApprovedPackagesChecker.ts b/libraries/rush-lib/src/logic/ApprovedPackagesChecker.ts
index c20f3b525d9..a0f773f5de8 100644
--- a/libraries/rush-lib/src/logic/ApprovedPackagesChecker.ts
+++ b/libraries/rush-lib/src/logic/ApprovedPackagesChecker.ts
@@ -9,17 +9,17 @@ import type { RushConfigurationProject } from '../api/RushConfigurationProject';
 import { DependencySpecifier } from './DependencySpecifier';
 
 export class ApprovedPackagesChecker {
-  private readonly _rushConfiguration: RushConfiguration;
-  private _approvedPackagesPolicy: ApprovedPackagesPolicy;
-  private _filesAreOutOfDate: boolean;
+  readonly #rushConfiguration: RushConfiguration;
+  #approvedPackagesPolicy: ApprovedPackagesPolicy;
+  #filesAreOutOfDate: boolean;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
-    this._approvedPackagesPolicy = this._rushConfiguration.approvedPackagesPolicy;
-    this._filesAreOutOfDate = false;
+    this.#rushConfiguration = rushConfiguration;
+    this.#approvedPackagesPolicy = this.#rushConfiguration.approvedPackagesPolicy;
+    this.#filesAreOutOfDate = false;
 
-    if (this._approvedPackagesPolicy.enabled) {
-      this._updateApprovedPackagesPolicy();
+    if (this.#approvedPackagesPolicy.enabled) {
+      this.#updateApprovedPackagesPolicy();
     }
   }
 
@@ -27,7 +27,7 @@ export class ApprovedPackagesChecker {
    * If true, the files on disk are out of date.
    */
   public get approvedPackagesFilesAreOutOfDate(): boolean {
-    return this._filesAreOutOfDate;
+    return this.#filesAreOutOfDate;
   }
 
   /**
@@ -39,25 +39,25 @@ export class ApprovedPackagesChecker {
    * If the "approvedPackagesPolicy" feature is not enabled, then no action is taken.
    */
   public rewriteConfigFiles(): void {
-    const approvedPackagesPolicy: ApprovedPackagesPolicy = this._rushConfiguration.approvedPackagesPolicy;
+    const approvedPackagesPolicy: ApprovedPackagesPolicy = this.#rushConfiguration.approvedPackagesPolicy;
     if (approvedPackagesPolicy.enabled) {
       approvedPackagesPolicy.browserApprovedPackages.saveToFile();
       approvedPackagesPolicy.nonbrowserApprovedPackages.saveToFile();
     }
   }
 
-  private _updateApprovedPackagesPolicy(): void {
-    for (const rushProject of this._rushConfiguration.projects) {
+  #updateApprovedPackagesPolicy(): void {
+    for (const rushProject of this.#rushConfiguration.projects) {
       const packageJson: IPackageJson = rushProject.packageJson;
 
-      this._collectDependencies(packageJson.dependencies, this._approvedPackagesPolicy, rushProject);
-      this._collectDependencies(packageJson.devDependencies, this._approvedPackagesPolicy, rushProject);
-      this._collectDependencies(packageJson.peerDependencies, this._approvedPackagesPolicy, rushProject);
-      this._collectDependencies(packageJson.optionalDependencies, this._approvedPackagesPolicy, rushProject);
+      this.#collectDependencies(packageJson.dependencies, this.#approvedPackagesPolicy, rushProject);
+      this.#collectDependencies(packageJson.devDependencies, this.#approvedPackagesPolicy, rushProject);
+      this.#collectDependencies(packageJson.peerDependencies, this.#approvedPackagesPolicy, rushProject);
+      this.#collectDependencies(packageJson.optionalDependencies, this.#approvedPackagesPolicy, rushProject);
     }
   }
 
-  private _collectDependencies(
+  #collectDependencies(
     dependencies: { [key: string]: string } | undefined,
     approvedPackagesPolicy: ApprovedPackagesPolicy,
     rushProject: RushConfigurationProject
@@ -80,7 +80,7 @@ export class ApprovedPackagesChecker {
           referencedPackageName = dependencySpecifier.aliasTarget.packageName;
         }
 
-        const scope: string = this._rushConfiguration.packageNameParser.getScope(referencedPackageName);
+        const scope: string = this.#rushConfiguration.packageNameParser.getScope(referencedPackageName);
 
         // Make sure the scope isn't something like "@types" which should be ignored
         if (!approvedPackagesPolicy.ignoredNpmScopes.has(scope) && rushProject.reviewCategory) {
@@ -102,7 +102,7 @@ export class ApprovedPackagesChecker {
             );
           }
 
-          this._filesAreOutOfDate = this._filesAreOutOfDate || updated;
+          this.#filesAreOutOfDate = this.#filesAreOutOfDate || updated;
         }
       }
     }
diff --git a/libraries/rush-lib/src/logic/Autoinstaller.ts b/libraries/rush-lib/src/logic/Autoinstaller.ts
index a47dd0d89be..0b326bdc970 100644
--- a/libraries/rush-lib/src/logic/Autoinstaller.ts
+++ b/libraries/rush-lib/src/logic/Autoinstaller.ts
@@ -35,15 +35,15 @@ export interface IAutoinstallerOptions {
 export class Autoinstaller {
   public readonly name: string;
 
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _rushGlobalFolder: RushGlobalFolder;
-  private readonly _restrictConsoleOutput: boolean;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #rushGlobalFolder: RushGlobalFolder;
+  readonly #restrictConsoleOutput: boolean;
 
   public constructor(options: IAutoinstallerOptions) {
     this.name = options.autoinstallerName;
-    this._rushConfiguration = options.rushConfiguration;
-    this._rushGlobalFolder = options.rushGlobalFolder;
-    this._restrictConsoleOutput =
+    this.#rushConfiguration = options.rushConfiguration;
+    this.#rushGlobalFolder = options.rushGlobalFolder;
+    this.#restrictConsoleOutput =
       options.restrictConsoleOutput ?? RushCommandLineParser.shouldRestrictConsoleOutput();
 
     Autoinstaller.validateName(this.name);
@@ -51,21 +51,21 @@ export class Autoinstaller {
 
   // Example: .../common/autoinstallers/my-task
   public get folderFullPath(): string {
-    return path.join(this._rushConfiguration.commonAutoinstallersFolder, this.name);
+    return path.join(this.#rushConfiguration.commonAutoinstallersFolder, this.name);
   }
 
   // Example: .../common/autoinstallers/my-task/package-lock.yaml
   public get shrinkwrapFilePath(): string {
     return path.join(
-      this._rushConfiguration.commonAutoinstallersFolder,
+      this.#rushConfiguration.commonAutoinstallersFolder,
       this.name,
-      this._rushConfiguration.shrinkwrapFilename
+      this.#rushConfiguration.shrinkwrapFilename
     );
   }
 
   // Example: .../common/autoinstallers/my-task/package.json
   public get packageJsonPath(): string {
-    return path.join(this._rushConfiguration.commonAutoinstallersFolder, this.name, 'package.json');
+    return path.join(this.#rushConfiguration.commonAutoinstallersFolder, this.name, 'package.json');
   }
 
   public static validateName(autoinstallerName: string): void {
@@ -88,19 +88,19 @@ export class Autoinstaller {
     }
 
     await InstallHelpers.ensureLocalPackageManagerAsync(
-      this._rushConfiguration,
-      this._rushGlobalFolder,
+      this.#rushConfiguration,
+      this.#rushGlobalFolder,
       RushConstants.defaultMaxInstallAttempts,
-      this._restrictConsoleOutput
+      this.#restrictConsoleOutput
     );
 
     // Example: common/autoinstallers/my-task/package.json
     const relativePathForLogs: string = path.relative(
-      this._rushConfiguration.rushJsonFolder,
+      this.#rushConfiguration.rushJsonFolder,
       autoinstallerFullPath
     );
 
-    this._logIfConsoleOutputIsNotRestricted(`Acquiring lock for "${relativePathForLogs}" folder...`);
+    this.#logIfConsoleOutputIsNotRestricted(`Acquiring lock for "${relativePathForLogs}" folder...`);
 
     const lock: LockFile = await LockFile.acquireAsync(autoinstallerFullPath, 'autoinstaller');
 
@@ -117,10 +117,10 @@ export class Autoinstaller {
 
       const lastInstallFlag: LastInstallFlag = new LastInstallFlag(lastInstallFlagPath, {
         node: process.versions.node,
-        packageManager: this._rushConfiguration.packageManager,
-        packageManagerVersion: this._rushConfiguration.packageManagerToolVersion,
+        packageManager: this.#rushConfiguration.packageManager,
+        packageManagerVersion: this.#rushConfiguration.packageManagerToolVersion,
         packageJson: packageJson,
-        rushJsonFolder: this._rushConfiguration.rushJsonFolder
+        rushJsonFolder: this.#rushConfiguration.rushJsonFolder
       });
 
       // Example: ../common/autoinstallers/my-task/node_modules
@@ -131,9 +131,9 @@ export class Autoinstaller {
 
       if (isLastInstallFlagDirty || lock.dirtyWhenAcquired) {
         if (FileSystem.exists(nodeModulesFolder)) {
-          this._logIfConsoleOutputIsNotRestricted('Deleting old files from ' + nodeModulesFolder);
+          this.#logIfConsoleOutputIsNotRestricted('Deleting old files from ' + nodeModulesFolder);
           const recycler: AsyncRecycler = new AsyncRecycler(
-            `${this._rushConfiguration.commonTempFolder}/${RushConstants.rushRecyclerFolderName}`
+            `${this.#rushConfiguration.commonTempFolder}/${RushConstants.rushRecyclerFolderName}`
           );
           recycler.moveFolder(nodeModulesFolder);
           await recycler.startDeleteAllAsync();
@@ -141,17 +141,17 @@ export class Autoinstaller {
 
         // Copy: .../common/autoinstallers/my-task/.npmrc
         Utilities.syncNpmrc({
-          sourceNpmrcFolder: this._rushConfiguration.commonRushConfigFolder,
+          sourceNpmrcFolder: this.#rushConfiguration.commonRushConfigFolder,
           targetNpmrcFolder: autoinstallerFullPath,
-          supportEnvVarFallbackSyntax: this._rushConfiguration.isPnpm
+          supportEnvVarFallbackSyntax: this.#rushConfiguration.isPnpm
         });
 
-        this._logIfConsoleOutputIsNotRestricted(
+        this.#logIfConsoleOutputIsNotRestricted(
           `Installing dependencies under ${autoinstallerFullPath}...\n`
         );
 
         await Utilities.executeCommandAsync({
-          command: this._rushConfiguration.packageManagerToolFilename,
+          command: this.#rushConfiguration.packageManagerToolFilename,
           args: ['install', '--frozen-lockfile'],
           workingDirectory: autoinstallerFullPath,
           keepEnvironment: true
@@ -165,9 +165,9 @@ export class Autoinstaller {
           'If this file is deleted, Rush will assume that the node_modules folder has been cleaned and will reinstall it.'
         );
 
-        this._logIfConsoleOutputIsNotRestricted('Auto install completed successfully\n');
+        this.#logIfConsoleOutputIsNotRestricted('Auto install completed successfully\n');
       } else {
-        this._logIfConsoleOutputIsNotRestricted('Autoinstaller folder is already up to date\n');
+        this.#logIfConsoleOutputIsNotRestricted('Autoinstaller folder is already up to date\n');
       }
     } finally {
       // Ensure the lockfile is released when we are finished.
@@ -177,10 +177,10 @@ export class Autoinstaller {
 
   public async updateAsync(): Promise<void> {
     await InstallHelpers.ensureLocalPackageManagerAsync(
-      this._rushConfiguration,
-      this._rushGlobalFolder,
+      this.#rushConfiguration,
+      this.#rushGlobalFolder,
       RushConstants.defaultMaxInstallAttempts,
-      this._restrictConsoleOutput
+      this.#restrictConsoleOutput
     );
 
     const autoinstallerPackageJsonPath: string = path.join(this.folderFullPath, 'package.json');
@@ -189,7 +189,7 @@ export class Autoinstaller {
       throw new Error(`The specified autoinstaller path does not exist: ` + autoinstallerPackageJsonPath);
     }
 
-    this._logIfConsoleOutputIsNotRestricted(
+    this.#logIfConsoleOutputIsNotRestricted(
       `Updating autoinstaller package: ${autoinstallerPackageJsonPath}`
     );
 
@@ -197,16 +197,16 @@ export class Autoinstaller {
 
     if (await FileSystem.existsAsync(this.shrinkwrapFilePath)) {
       oldFileContents = FileSystem.readFile(this.shrinkwrapFilePath, { convertLineEndings: NewlineKind.Lf });
-      this._logIfConsoleOutputIsNotRestricted('Deleting ' + this.shrinkwrapFilePath);
+      this.#logIfConsoleOutputIsNotRestricted('Deleting ' + this.shrinkwrapFilePath);
       await FileSystem.deleteFileAsync(this.shrinkwrapFilePath);
-      if (this._rushConfiguration.isPnpm) {
+      if (this.#rushConfiguration.isPnpm) {
         // Workaround for https://github.com/pnpm/pnpm/issues/1890
         //
         // When "rush update-autoinstaller" is run, Rush deletes "common/autoinstallers/my-task/pnpm-lock.yaml"
         // so that a new lockfile will be generated. However "pnpm install" by design will try to recover
         // "pnpm-lock.yaml" from "my-task/node_modules/.pnpm/lock.yaml", which may prevent a full upgrade.
         // Deleting both files ensures that a new lockfile will always be generated.
-        const pnpmPackageManager: PnpmPackageManager = this._rushConfiguration
+        const pnpmPackageManager: PnpmPackageManager = this.#rushConfiguration
           .packageManagerWrapper as PnpmPackageManager;
         await FileSystem.deleteFileAsync(
           path.join(this.folderFullPath, pnpmPackageManager.internalShrinkwrapRelativePath)
@@ -224,33 +224,33 @@ export class Autoinstaller {
       );
     }
 
-    this._logIfConsoleOutputIsNotRestricted();
+    this.#logIfConsoleOutputIsNotRestricted();
 
     Utilities.syncNpmrc({
-      sourceNpmrcFolder: this._rushConfiguration.commonRushConfigFolder,
+      sourceNpmrcFolder: this.#rushConfiguration.commonRushConfigFolder,
       targetNpmrcFolder: this.folderFullPath,
-      supportEnvVarFallbackSyntax: this._rushConfiguration.isPnpm
+      supportEnvVarFallbackSyntax: this.#rushConfiguration.isPnpm
     });
 
     await Utilities.executeCommandAsync({
-      command: this._rushConfiguration.packageManagerToolFilename,
+      command: this.#rushConfiguration.packageManagerToolFilename,
       args: ['install'],
       workingDirectory: this.folderFullPath,
       keepEnvironment: true
     });
 
-    this._logIfConsoleOutputIsNotRestricted();
+    this.#logIfConsoleOutputIsNotRestricted();
 
-    if (this._rushConfiguration.packageManager === 'npm') {
-      this._logIfConsoleOutputIsNotRestricted(Colorize.bold('Running "npm shrinkwrap"...'));
+    if (this.#rushConfiguration.packageManager === 'npm') {
+      this.#logIfConsoleOutputIsNotRestricted(Colorize.bold('Running "npm shrinkwrap"...'));
       await Utilities.executeCommandAsync({
-        command: this._rushConfiguration.packageManagerToolFilename,
+        command: this.#rushConfiguration.packageManagerToolFilename,
         args: ['shrinkwrap'],
         workingDirectory: this.folderFullPath,
         keepEnvironment: true
       });
-      this._logIfConsoleOutputIsNotRestricted('"npm shrinkwrap" completed');
-      this._logIfConsoleOutputIsNotRestricted();
+      this.#logIfConsoleOutputIsNotRestricted('"npm shrinkwrap" completed');
+      this.#logIfConsoleOutputIsNotRestricted();
     }
 
     if (!(await FileSystem.existsAsync(this.shrinkwrapFilePath))) {
@@ -263,17 +263,17 @@ export class Autoinstaller {
       convertLineEndings: NewlineKind.Lf
     });
     if (oldFileContents !== newFileContents) {
-      this._logIfConsoleOutputIsNotRestricted(
+      this.#logIfConsoleOutputIsNotRestricted(
         Colorize.green('The shrinkwrap file has been updated.') + '  Please commit the updated file:'
       );
-      this._logIfConsoleOutputIsNotRestricted(`\n  ${this.shrinkwrapFilePath}`);
+      this.#logIfConsoleOutputIsNotRestricted(`\n  ${this.shrinkwrapFilePath}`);
     } else {
-      this._logIfConsoleOutputIsNotRestricted(Colorize.green('Already up to date.'));
+      this.#logIfConsoleOutputIsNotRestricted(Colorize.green('Already up to date.'));
     }
   }
 
-  private _logIfConsoleOutputIsNotRestricted(message?: string): void {
-    if (!this._restrictConsoleOutput) {
+  #logIfConsoleOutputIsNotRestricted(message?: string): void {
+    if (!this.#restrictConsoleOutput) {
       // eslint-disable-next-line no-console
       console.log(message ?? '');
     }
diff --git a/libraries/rush-lib/src/logic/ChangeFiles.ts b/libraries/rush-lib/src/logic/ChangeFiles.ts
index d63e011dbd7..3209198ce60 100644
--- a/libraries/rush-lib/src/logic/ChangeFiles.ts
+++ b/libraries/rush-lib/src/logic/ChangeFiles.ts
@@ -30,13 +30,13 @@ export class ChangeFiles {
   /**
    * Change file path relative to changes folder.
    */
-  private _files: string[] | undefined;
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _changesPath: string;
+  #files: string[] | undefined;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #changesPath: string;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
-    this._changesPath = rushConfiguration.changesFolder;
+    this.#rushConfiguration = rushConfiguration;
+    this.#changesPath = rushConfiguration.changesFolder;
   }
 
   /**
@@ -45,7 +45,7 @@ export class ChangeFiles {
   public async validateAsync(options: IValidateOptions): Promise<void> {
     const { terminal, filesToValidate, changedProjectNames, deletedProjectNames } = options;
     const schema: JsonSchema = JsonSchema.fromLoadedObject(schemaJson);
-    const rushConfiguration: RushConfiguration = this._rushConfiguration;
+    const rushConfiguration: RushConfiguration = this.#rushConfiguration;
     const {
       hotfixChangeEnabled,
       experimentsConfiguration: {
@@ -180,19 +180,19 @@ export class ChangeFiles {
    * Get the array of absolute paths of change files.
    */
   public async getAllChangeFilesAsync(): Promise<string[]> {
-    if (!this._files) {
+    if (!this.#files) {
       const { default: glob } = await import('fast-glob');
-      this._files = (await glob('**/*.json', { cwd: this._changesPath, absolute: true })) || [];
+      this.#files = (await glob('**/*.json', { cwd: this.#changesPath, absolute: true })) || [];
     }
 
-    return this._files;
+    return this.#files;
   }
 
   /**
    * Get the path of changes folder.
    */
   public getChangesPath(): string {
-    return this._changesPath;
+    return this.#changesPath;
   }
 
   /**
@@ -231,15 +231,15 @@ export class ChangeFiles {
         { concurrency: 5 }
       );
 
-      return await this._deleteFilesAsync(terminal, filesToDelete, shouldDelete);
+      return await this.#deleteFilesAsync(terminal, filesToDelete, shouldDelete);
     } else {
       // Delete all change files.
       const files: string[] = await this.getAllChangeFilesAsync();
-      return await this._deleteFilesAsync(terminal, files, shouldDelete);
+      return await this.#deleteFilesAsync(terminal, files, shouldDelete);
     }
   }
 
-  private async _deleteFilesAsync(
+  async #deleteFilesAsync(
     terminal: ITerminal,
     files: string[],
     shouldDelete: boolean
diff --git a/libraries/rush-lib/src/logic/ChangeManager.ts b/libraries/rush-lib/src/logic/ChangeManager.ts
index 7b891d37b7d..b5ee07d8e58 100644
--- a/libraries/rush-lib/src/logic/ChangeManager.ts
+++ b/libraries/rush-lib/src/logic/ChangeManager.ts
@@ -19,17 +19,17 @@ import { ChangelogGenerator } from './ChangelogGenerator';
  * can be applied to package.json and change logs.
  */
 export class ChangeManager {
-  private _prereleaseToken!: PrereleaseToken;
-  private _orderedChanges!: IChangeInfo[];
-  private _allPackages!: ReadonlyMap<string, RushConfigurationProject>;
-  private _allChanges!: IChangeRequests;
-  private _changeFiles!: ChangeFiles;
-  private _rushConfiguration: RushConfiguration;
-  private _projectsToExclude: Set<string> | undefined;
+  #prereleaseToken!: PrereleaseToken;
+  #orderedChanges!: IChangeInfo[];
+  #allPackages!: ReadonlyMap<string, RushConfigurationProject>;
+  #allChanges!: IChangeRequests;
+  #changeFiles!: ChangeFiles;
+  #rushConfiguration: RushConfiguration;
+  #projectsToExclude: Set<string> | undefined;
 
   public constructor(rushConfiguration: RushConfiguration, projectsToExclude?: Set<string> | undefined) {
-    this._rushConfiguration = rushConfiguration;
-    this._projectsToExclude = projectsToExclude;
+    this.#rushConfiguration = rushConfiguration;
+    this.#projectsToExclude = projectsToExclude;
   }
 
   /**
@@ -41,41 +41,41 @@ export class ChangeManager {
     prereleaseToken: PrereleaseToken = new PrereleaseToken(),
     includeCommitDetails: boolean = false
   ): Promise<void> {
-    this._allPackages = this._rushConfiguration.projectsByName;
+    this.#allPackages = this.#rushConfiguration.projectsByName;
 
-    this._prereleaseToken = prereleaseToken;
+    this.#prereleaseToken = prereleaseToken;
 
-    this._changeFiles = new ChangeFiles(this._rushConfiguration);
-    this._allChanges = await PublishUtilities.findChangeRequestsAsync(
-      this._allPackages,
-      this._rushConfiguration,
-      this._changeFiles,
+    this.#changeFiles = new ChangeFiles(this.#rushConfiguration);
+    this.#allChanges = await PublishUtilities.findChangeRequestsAsync(
+      this.#allPackages,
+      this.#rushConfiguration,
+      this.#changeFiles,
       includeCommitDetails,
-      this._prereleaseToken,
-      this._projectsToExclude
+      this.#prereleaseToken,
+      this.#projectsToExclude
     );
-    this._orderedChanges = PublishUtilities.sortChangeRequests(this._allChanges.packageChanges);
+    this.#orderedChanges = PublishUtilities.sortChangeRequests(this.#allChanges.packageChanges);
   }
 
   public hasChanges(): boolean {
     return (
-      (this._orderedChanges && this._orderedChanges.length > 0) ||
-      (this._allChanges && this._allChanges.versionPolicyChanges.size > 0)
+      (this.#orderedChanges && this.#orderedChanges.length > 0) ||
+      (this.#allChanges && this.#allChanges.versionPolicyChanges.size > 0)
     );
   }
 
   public get packageChanges(): IChangeInfo[] {
-    return this._orderedChanges;
+    return this.#orderedChanges;
   }
 
   public get allPackages(): ReadonlyMap<string, RushConfigurationProject> {
-    return this._allPackages;
+    return this.#allPackages;
   }
 
   public validateChanges(versionConfig: VersionPolicyConfiguration): void {
-    this._allChanges.packageChanges.forEach((change, projectName) => {
+    this.#allChanges.packageChanges.forEach((change, projectName) => {
       const projectInfo: RushConfigurationProject | undefined =
-        this._rushConfiguration.getProjectByName(projectName);
+        this.#rushConfiguration.getProjectByName(projectName);
       if (projectInfo) {
         if (projectInfo.versionPolicy) {
           projectInfo.versionPolicy.validate(change.newVersion!, projectName);
@@ -95,8 +95,8 @@ export class ChangeManager {
     }
 
     // Update all the changed version policies
-    this._allChanges.versionPolicyChanges.forEach((versionPolicyChange, versionPolicyName) => {
-      this._rushConfiguration.versionPolicyConfiguration.update(
+    this.#allChanges.versionPolicyChanges.forEach((versionPolicyChange, versionPolicyName) => {
+      this.#rushConfiguration.versionPolicyConfiguration.update(
         versionPolicyName,
         versionPolicyChange.newVersion,
         shouldCommit
@@ -105,12 +105,12 @@ export class ChangeManager {
 
     // Apply all changes to package.json files.
     const updatedPackages: Map<string, IPackageJson> = PublishUtilities.updatePackages(
-      this._allChanges,
-      this._allPackages,
-      this._rushConfiguration,
+      this.#allChanges,
+      this.#allPackages,
+      this.#rushConfiguration,
       shouldCommit,
-      this._prereleaseToken,
-      this._projectsToExclude
+      this.#prereleaseToken,
+      this.#projectsToExclude
     );
 
     return updatedPackages;
@@ -119,17 +119,17 @@ export class ChangeManager {
   public async updateChangelogAsync(terminal: ITerminal, shouldCommit: boolean): Promise<void> {
     // Do not update changelog or delete the change files for prerelease.
     // Save them for the official release.
-    if (!this._prereleaseToken.hasValue) {
+    if (!this.#prereleaseToken.hasValue) {
       // Update changelogs.
       const updatedChangelogs: IChangelog[] = ChangelogGenerator.updateChangelogs(
-        this._allChanges,
-        this._allPackages,
-        this._rushConfiguration,
+        this.#allChanges,
+        this.#allPackages,
+        this.#rushConfiguration,
         shouldCommit
       );
 
       // Remove the change request files only if "-a" was provided.
-      await this._changeFiles.deleteAllAsync(terminal, shouldCommit, updatedChangelogs);
+      await this.#changeFiles.deleteAllAsync(terminal, shouldCommit, updatedChangelogs);
     }
   }
 }
diff --git a/libraries/rush-lib/src/logic/DependencyAnalyzer.ts b/libraries/rush-lib/src/logic/DependencyAnalyzer.ts
index cca5a86385e..93ef26db116 100644
--- a/libraries/rush-lib/src/logic/DependencyAnalyzer.ts
+++ b/libraries/rush-lib/src/logic/DependencyAnalyzer.ts
@@ -31,11 +31,11 @@ export interface IDependencyAnalysis {
 let _dependencyAnalyzerByRushConfiguration: WeakMap<RushConfiguration, DependencyAnalyzer> | undefined;
 
 export class DependencyAnalyzer {
-  private _rushConfiguration: RushConfiguration;
-  private _analysisByVariantBySubspace: Map<string, WeakMap<Subspace, IDependencyAnalysis>> | undefined;
+  #rushConfiguration: RushConfiguration;
+  #analysisByVariantBySubspace: Map<string, WeakMap<Subspace, IDependencyAnalysis>> | undefined;
 
   private constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   public static forRushConfiguration(rushConfiguration: RushConfiguration): DependencyAnalyzer {
@@ -62,22 +62,22 @@ export class DependencyAnalyzer {
     // with a variant created by the user
     const variantKey: string = variant || '';
 
-    if (!this._analysisByVariantBySubspace) {
-      this._analysisByVariantBySubspace = new Map();
+    if (!this.#analysisByVariantBySubspace) {
+      this.#analysisByVariantBySubspace = new Map();
     }
 
-    const subspaceToAnalyze: Subspace = subspace || this._rushConfiguration.defaultSubspace;
+    const subspaceToAnalyze: Subspace = subspace || this.#rushConfiguration.defaultSubspace;
     let analysisForVariant: WeakMap<Subspace, IDependencyAnalysis> | undefined =
-      this._analysisByVariantBySubspace.get(variantKey);
+      this.#analysisByVariantBySubspace.get(variantKey);
 
     if (!analysisForVariant) {
       analysisForVariant = new WeakMap();
-      this._analysisByVariantBySubspace.set(variantKey, analysisForVariant);
+      this.#analysisByVariantBySubspace.set(variantKey, analysisForVariant);
     }
 
     let analysisForSubspace: IDependencyAnalysis | undefined = analysisForVariant.get(subspaceToAnalyze);
     if (!analysisForSubspace) {
-      analysisForSubspace = this._getAnalysisInternal(subspaceToAnalyze, variant, addAction);
+      analysisForSubspace = this.#getAnalysisInternal(subspaceToAnalyze, variant, addAction);
 
       analysisForVariant.set(subspaceToAnalyze, analysisForSubspace);
     }
@@ -91,7 +91,7 @@ export class DependencyAnalyzer {
    * @remarks
    * The result of this function is not cached.
    */
-  private _getAnalysisInternal(
+  #getAnalysisInternal(
     subspace: Subspace,
     variant: string | undefined,
     addAction: boolean
@@ -103,8 +103,8 @@ export class DependencyAnalyzer {
       ReadonlyArray<string>
     > = commonVersionsConfiguration.allowedAlternativeVersions;
 
-    let projectsToProcess: RushConfigurationProject[] = this._rushConfiguration.projects;
-    if (addAction && this._rushConfiguration.subspacesFeatureEnabled) {
+    let projectsToProcess: RushConfigurationProject[] = this.#rushConfiguration.projects;
+    if (addAction && this.#rushConfiguration.subspacesFeatureEnabled) {
       projectsToProcess = subspace.getProjects();
     }
 
@@ -127,7 +127,7 @@ export class DependencyAnalyzer {
 
         // Is it a local project?
         const localProject: RushConfigurationProject | undefined =
-          this._rushConfiguration.getProjectByName(dependencyName);
+          this.#rushConfiguration.getProjectByName(dependencyName);
         if (localProject) {
           if (
             !project.decoupledLocalDependencies.has(dependencyName) &&
diff --git a/libraries/rush-lib/src/logic/EventHooksManager.ts b/libraries/rush-lib/src/logic/EventHooksManager.ts
index a7324a8f119..a3b782c6160 100644
--- a/libraries/rush-lib/src/logic/EventHooksManager.ts
+++ b/libraries/rush-lib/src/logic/EventHooksManager.ts
@@ -11,22 +11,22 @@ import type { RushConfiguration } from '../api/RushConfiguration';
 import { EnvironmentVariableNames } from '../api/EnvironmentConfiguration';
 
 export class EventHooksManager {
-  private _rushConfiguration: RushConfiguration;
-  private _eventHooks: EventHooks;
-  private _commonTempFolder: string;
+  #rushConfiguration: RushConfiguration;
+  #eventHooks: EventHooks;
+  #commonTempFolder: string;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
-    this._eventHooks = rushConfiguration.eventHooks;
-    this._commonTempFolder = rushConfiguration.commonTempFolder;
+    this.#rushConfiguration = rushConfiguration;
+    this.#eventHooks = rushConfiguration.eventHooks;
+    this.#commonTempFolder = rushConfiguration.commonTempFolder;
   }
 
   public handle(event: Event, isDebug: boolean, ignoreHooks: boolean): void {
-    if (!this._eventHooks) {
+    if (!this.#eventHooks) {
       return;
     }
 
-    const scripts: string[] = this._eventHooks.get(event);
+    const scripts: string[] = this.#eventHooks.get(event);
     if (scripts.length > 0) {
       if (ignoreHooks) {
         // eslint-disable-next-line no-console
@@ -40,7 +40,7 @@ export class EventHooksManager {
 
       const printEventHooksOutputToConsole: boolean | undefined =
         isDebug ||
-        this._rushConfiguration.experimentsConfiguration.configuration.printEventHooksOutputToConsole;
+        this.#rushConfiguration.experimentsConfiguration.configuration.printEventHooksOutputToConsole;
       scripts.forEach((script) => {
         try {
           const environment: IEnvironment = { ...process.env };
@@ -51,9 +51,9 @@ export class EventHooksManager {
           environment[EnvironmentVariableNames.RUSH_INVOKED_ARGS] = JSON.stringify(process.argv);
 
           Utilities.executeLifecycleCommand(script, {
-            rushConfiguration: this._rushConfiguration,
-            workingDirectory: this._rushConfiguration.rushJsonFolder,
-            initCwd: this._commonTempFolder,
+            rushConfiguration: this.#rushConfiguration,
+            workingDirectory: this.#rushConfiguration.rushJsonFolder,
+            initCwd: this.#commonTempFolder,
             handleOutput: !printEventHooksOutputToConsole,
             initialEnvironment: environment,
             environmentPathOptions: {
diff --git a/libraries/rush-lib/src/logic/Git.ts b/libraries/rush-lib/src/logic/Git.ts
index 36386d4224d..4b4345dfca3 100644
--- a/libraries/rush-lib/src/logic/Git.ts
+++ b/libraries/rush-lib/src/logic/Git.ts
@@ -31,29 +31,29 @@ export interface IGetBlobOptions {
 }
 
 export class Git {
-  private readonly _rushConfiguration: RushConfiguration;
-  private _checkedGitPath: boolean = false;
-  private _gitPath: string | undefined;
-  private _checkedGitInfo: boolean = false;
-  private _gitInfo: gitInfo.GitRepoInfo | undefined;
+  readonly #rushConfiguration: RushConfiguration;
+  #checkedGitPath: boolean = false;
+  #gitPath: string | undefined;
+  #checkedGitInfo: boolean = false;
+  #gitInfo: gitInfo.GitRepoInfo | undefined;
 
-  private _gitEmailResult: IResultOrError<string> | undefined = undefined;
-  private _gitHooksPath: IResultOrError<string> | undefined = undefined;
+  #gitEmailResult: IResultOrError<string> | undefined = undefined;
+  #gitHooksPath: IResultOrError<string> | undefined = undefined;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   /**
    * Returns the path to the Git binary if found. Otherwise, return undefined.
    */
   public get gitPath(): string | undefined {
-    if (!this._checkedGitPath) {
-      this._gitPath = EnvironmentConfiguration.gitBinaryPath || Executable.tryResolve('git');
-      this._checkedGitPath = true;
+    if (!this.#checkedGitPath) {
+      this.#gitPath = EnvironmentConfiguration.gitBinaryPath || Executable.tryResolve('git');
+      this.#checkedGitPath = true;
     }
 
-    return this._gitPath;
+    return this.#gitPath;
   }
 
   public getGitPathOrThrow(): string {
@@ -97,7 +97,7 @@ export class Git {
   public async getGitEmailAsync(): Promise<string> {
     // Determine the user's account
     // Ex: "bob@example.com"
-    const { error, result } = await this._tryGetGitEmailAsync();
+    const { error, result } = await this.#tryGetGitEmailAsync();
     if (error) {
       // eslint-disable-next-line no-console
       console.log(
@@ -127,7 +127,7 @@ export class Git {
           '',
           `If you didn't configure your email yet, try something like this:`,
           '',
-          ...GitEmailPolicy.getEmailExampleLines(this._rushConfiguration),
+          ...GitEmailPolicy.getEmailExampleLines(this.#rushConfiguration),
           ''
         ].join('\n')
       );
@@ -162,7 +162,7 @@ export class Git {
       /* ignore errors from true-case-path */
     }
     const defaultHooksPath: string = path.resolve(commonGitDir, 'hooks');
-    const hooksResult: IResultOrError<string> = await this._tryGetGitHooksPathAsync();
+    const hooksResult: IResultOrError<string> = await this.#tryGetGitHooksPathAsync();
     if (hooksResult.error) {
       // eslint-disable-next-line no-console
       console.log(
@@ -180,7 +180,7 @@ export class Git {
 
     if (hooksResult.result) {
       const absoluteHooksPath: string = path.resolve(
-        this._rushConfiguration.rushJsonFolder,
+        this.#rushConfiguration.rushJsonFolder,
         hooksResult.result
       );
       return absoluteHooksPath === defaultHooksPath;
@@ -208,21 +208,21 @@ export class Git {
    * Returns undefined if rush.json is not under a Git working tree.
    */
   public getGitInfo(): Readonly<gitInfo.GitRepoInfo> | undefined {
-    if (!this._checkedGitInfo) {
+    if (!this.#checkedGitInfo) {
       let repoInfo: gitInfo.GitRepoInfo | undefined;
       try {
         // gitInfo() shouldn't usually throw, but wrapping in a try/catch just in case
-        repoInfo = gitInfo(this._rushConfiguration.rushJsonFolder);
+        repoInfo = gitInfo(this.#rushConfiguration.rushJsonFolder);
       } catch (ex) {
         // if there's an error, assume we're not in a Git working tree
       }
 
       if (repoInfo && this.isPathUnderGitWorkingTree(repoInfo)) {
-        this._gitInfo = repoInfo;
+        this.#gitInfo = repoInfo;
       }
-      this._checkedGitInfo = true;
+      this.#checkedGitInfo = true;
     }
-    return this._gitInfo;
+    return this.#gitInfo;
   }
 
   public async getMergeBaseAsync(
@@ -231,7 +231,7 @@ export class Git {
     shouldFetch: boolean = false
   ): Promise<string> {
     if (shouldFetch) {
-      this._fetchRemoteBranch(targetBranch, terminal);
+      this.#fetchRemoteBranch(targetBranch, terminal);
     }
 
     const gitPath: string = this.getGitPathOrThrow();
@@ -282,7 +282,7 @@ export class Git {
     pathPrefix?: string
   ): Promise<string[]> {
     if (!skipFetch) {
-      this._fetchRemoteBranch(targetBranch, terminal);
+      this.#fetchRemoteBranch(targetBranch, terminal);
     }
 
     const gitPath: string = this.getGitPathOrThrow();
@@ -320,7 +320,7 @@ export class Git {
    * @param rushConfiguration - rush configuration
    */
   public async getRemoteDefaultBranchAsync(): Promise<string> {
-    const repositoryUrls: string[] = this._rushConfiguration.repositoryUrls;
+    const repositoryUrls: string[] = this.#rushConfiguration.repositoryUrls;
     if (repositoryUrls.length > 0) {
       const gitPath: string = this.getGitPathOrThrow();
       const output: string = (await this._executeGitCommandAndCaptureOutputAsync(gitPath, ['remote'])).trim();
@@ -365,7 +365,7 @@ export class Git {
           );
         }
 
-        return `${matchingRemotes[0]}/${this._rushConfiguration.repositoryDefaultBranch}`;
+        return `${matchingRemotes[0]}/${this.#rushConfiguration.repositoryDefaultBranch}`;
       } else {
         const errorMessage: string =
           repositoryUrls.length > 1
@@ -376,7 +376,7 @@ export class Git {
         // eslint-disable-next-line no-console
         console.log(Colorize.yellow(errorMessage + 'Detected changes are likely to be incorrect.'));
 
-        return this._rushConfiguration.repositoryDefaultFullyQualifiedRemoteBranch;
+        return this.#rushConfiguration.repositoryDefaultFullyQualifiedRemoteBranch;
       }
     } else {
       // eslint-disable-next-line no-console
@@ -385,7 +385,7 @@ export class Git {
           `A git remote URL has not been specified in ${RushConstants.rushJsonFilename}. Setting the baseline remote URL is recommended.`
         )
       );
-      return this._rushConfiguration.repositoryDefaultFullyQualifiedRemoteBranch;
+      return this.#rushConfiguration.repositoryDefaultFullyQualifiedRemoteBranch;
     }
   }
 
@@ -427,7 +427,7 @@ export class Git {
   }
 
   public getTagSeparator(): string {
-    return this._rushConfiguration.gitTagSeparator || DEFAULT_GIT_TAG_SEPARATOR;
+    return this.#rushConfiguration.gitTagSeparator || DEFAULT_GIT_TAG_SEPARATOR;
   }
 
   public async getGitStatusAsync(): Promise<Iterable<IGitStatusEntry>> {
@@ -524,7 +524,7 @@ export class Git {
    * returns user.email config
    */
   public async tryGetGitEmailAsync(): Promise<string | undefined> {
-    const { result } = await this._tryGetGitEmailAsync();
+    const { result } = await this.#tryGetGitEmailAsync();
     return result;
   }
 
@@ -538,12 +538,12 @@ export class Git {
       await this._executeGitCommandAndCaptureOutputAsync(
         gitPath,
         ['add', '--', ...pattern],
-        this._rushConfiguration.changesFolder
+        this.#rushConfiguration.changesFolder
       );
       await this._executeGitCommandAndCaptureOutputAsync(
         gitPath,
         ['commit', '-m', message, '--', ...pattern],
-        this._rushConfiguration.changesFolder
+        this.#rushConfiguration.changesFolder
       );
     } catch (error) {
       terminal.writeErrorLine(`ERROR: Cannot stage and commit git changes ${(error as Error).message}`);
@@ -554,45 +554,45 @@ export class Git {
    * Returns an object containing either the result of the `git config user.email`
    * command or an error.
    */
-  private async _tryGetGitEmailAsync(): Promise<IResultOrError<string>> {
-    if (this._gitEmailResult === undefined) {
+  async #tryGetGitEmailAsync(): Promise<IResultOrError<string>> {
+    if (this.#gitEmailResult === undefined) {
       const gitPath: string = this.getGitPathOrThrow();
       try {
-        this._gitEmailResult = {
+        this.#gitEmailResult = {
           result: (
             await this._executeGitCommandAndCaptureOutputAsync(gitPath, ['config', 'user.email'])
           ).trim()
         };
       } catch (e) {
-        this._gitEmailResult = {
+        this.#gitEmailResult = {
           error: e as Error
         };
       }
     }
 
-    return this._gitEmailResult;
+    return this.#gitEmailResult;
   }
 
-  private async _tryGetGitHooksPathAsync(): Promise<IResultOrError<string>> {
-    if (this._gitHooksPath === undefined) {
+  async #tryGetGitHooksPathAsync(): Promise<IResultOrError<string>> {
+    if (this.#gitHooksPath === undefined) {
       const gitPath: string = this.getGitPathOrThrow();
       try {
-        this._gitHooksPath = {
+        this.#gitHooksPath = {
           result: (
             await this._executeGitCommandAndCaptureOutputAsync(gitPath, ['rev-parse', '--git-path', 'hooks'])
           ).trim()
         };
       } catch (e) {
-        this._gitHooksPath = {
+        this.#gitHooksPath = {
           error: e as Error
         };
       }
     }
 
-    return this._gitHooksPath;
+    return this.#gitHooksPath;
   }
 
-  private _tryFetchRemoteBranch(remoteBranchName: string): boolean {
+  #tryFetchRemoteBranch(remoteBranchName: string): boolean {
     const firstSlashIndex: number = remoteBranchName.indexOf('/');
     if (firstSlashIndex === -1) {
       throw new Error(
@@ -614,10 +614,10 @@ export class Git {
     return spawnResult.status === 0;
   }
 
-  private _fetchRemoteBranch(remoteBranchName: string, terminal: ITerminal): void {
+  #fetchRemoteBranch(remoteBranchName: string, terminal: ITerminal): void {
     // eslint-disable-next-line no-console
     console.log(`Checking for updates to ${remoteBranchName}...`);
-    const fetchResult: boolean = this._tryFetchRemoteBranch(remoteBranchName);
+    const fetchResult: boolean = this.#tryFetchRemoteBranch(remoteBranchName);
     if (!fetchResult) {
       terminal.writeWarningLine(
         `Error fetching git remote branch ${remoteBranchName}. Detected changed files may be incorrect.`
@@ -631,7 +631,7 @@ export class Git {
   public async _executeGitCommandAndCaptureOutputAsync(
     gitPath: string,
     args: string[],
-    workingDirectory: string = this._rushConfiguration.rushJsonFolder
+    workingDirectory: string = this.#rushConfiguration.rushJsonFolder
   ): Promise<string> {
     try {
       return await Utilities.executeCommandAndCaptureOutputAsync({
diff --git a/libraries/rush-lib/src/logic/InteractiveUpgrader.ts b/libraries/rush-lib/src/logic/InteractiveUpgrader.ts
index a9a2e855179..ff7784fadd3 100644
--- a/libraries/rush-lib/src/logic/InteractiveUpgrader.ts
+++ b/libraries/rush-lib/src/logic/InteractiveUpgrader.ts
@@ -14,31 +14,31 @@ interface IUpgradeInteractiveDeps {
 }
 
 export class InteractiveUpgrader {
-  private readonly _rushConfiguration: RushConfiguration;
+  readonly #rushConfiguration: RushConfiguration;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   public async upgradeAsync(): Promise<IUpgradeInteractiveDeps> {
-    const rushProject: RushConfigurationProject = await this._getUserSelectedProjectForUpgradeAsync();
+    const rushProject: RushConfigurationProject = await this.#getUserSelectedProjectForUpgradeAsync();
 
     const dependenciesState: INpmCheckPackageSummary[] =
-      await this._getPackageDependenciesStatusAsync(rushProject);
+      await this.#getPackageDependenciesStatusAsync(rushProject);
 
     const depsToUpgrade: IDepsToUpgradeAnswers =
-      await this._getUserSelectedDependenciesToUpgradeAsync(dependenciesState);
+      await this.#getUserSelectedDependenciesToUpgradeAsync(dependenciesState);
     return { projects: [rushProject], depsToUpgrade };
   }
 
-  private async _getUserSelectedDependenciesToUpgradeAsync(
+  async #getUserSelectedDependenciesToUpgradeAsync(
     packages: INpmCheckPackageSummary[]
   ): Promise<IDepsToUpgradeAnswers> {
     return upgradeInteractive(packages);
   }
 
-  private async _getUserSelectedProjectForUpgradeAsync(): Promise<RushConfigurationProject> {
-    const projects: RushConfigurationProject[] | undefined = this._rushConfiguration.projects;
+  async #getUserSelectedProjectForUpgradeAsync(): Promise<RushConfigurationProject> {
+    const projects: RushConfigurationProject[] | undefined = this.#rushConfiguration.projects;
 
     const { default: search } = await import('@inquirer/search');
 
@@ -62,7 +62,7 @@ export class InteractiveUpgrader {
     });
   }
 
-  private async _getPackageDependenciesStatusAsync(
+  async #getPackageDependenciesStatusAsync(
     rushProject: RushConfigurationProject
   ): Promise<INpmCheckPackageSummary[]> {
     const { projectFolder } = rushProject;
diff --git a/libraries/rush-lib/src/logic/PackageJsonUpdater.ts b/libraries/rush-lib/src/logic/PackageJsonUpdater.ts
index 3a1e4789fbb..c6e1f49cf8c 100644
--- a/libraries/rush-lib/src/logic/PackageJsonUpdater.ts
+++ b/libraries/rush-lib/src/logic/PackageJsonUpdater.ts
@@ -100,18 +100,18 @@ export interface IRemoveProjectOptions extends IBaseUpdateProjectOptions {}
  * @internal
  */
 export class PackageJsonUpdater {
-  private readonly _terminal: ITerminal;
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _rushGlobalFolder: RushGlobalFolder;
+  readonly #terminal: ITerminal;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #rushGlobalFolder: RushGlobalFolder;
 
   public constructor(
     terminal: ITerminal,
     rushConfiguration: RushConfiguration,
     rushGlobalFolder: RushGlobalFolder
   ) {
-    this._terminal = terminal;
-    this._rushConfiguration = rushConfiguration;
-    this._rushGlobalFolder = rushGlobalFolder;
+    this.#terminal = terminal;
+    this.#rushConfiguration = rushConfiguration;
+    this.#rushGlobalFolder = rushGlobalFolder;
   }
 
   /**
@@ -125,7 +125,7 @@ export class PackageJsonUpdater {
       './DependencyAnalyzer'
     );
     const dependencyAnalyzer: DependencyAnalyzer = DependencyAnalyzer.forRushConfiguration(
-      this._rushConfiguration
+      this.#rushConfiguration
     );
     const {
       allVersionsByPackageName,
@@ -138,14 +138,14 @@ export class PackageJsonUpdater {
     const peerDependenciesToUpdate: Record<string, string> = {};
 
     for (const { moduleName, latest: latestVersion, packageJson, devDependency } of packagesToAdd) {
-      const inferredRangeStyle: SemVerStyle = this._cheaplyDetectSemVerRangeStyle(packageJson);
+      const inferredRangeStyle: SemVerStyle = this.#cheaplyDetectSemVerRangeStyle(packageJson);
       const implicitlyPreferredVersion: string | undefined =
         implicitlyPreferredVersionByPackageName.get(moduleName);
 
       const explicitlyPreferredVersion: string | undefined =
         commonVersionsConfiguration.preferredVersions.get(moduleName);
 
-      const version: string = await this._getNormalizedVersionSpecAsync(
+      const version: string = await this.#getNormalizedVersionSpecAsync(
         projects,
         moduleName,
         latestVersion,
@@ -161,10 +161,10 @@ export class PackageJsonUpdater {
         dependenciesToUpdate[moduleName] = version;
       }
 
-      this._terminal.writeLine(
+      this.#terminal.writeLine(
         Colorize.green(`Updating projects to use `) + moduleName + '@' + Colorize.cyan(version)
       );
-      this._terminal.writeLine();
+      this.#terminal.writeLine();
 
       const existingSpecifiedVersions: Set<string> | undefined = allVersionsByPackageName.get(moduleName);
       if (
@@ -215,10 +215,10 @@ export class PackageJsonUpdater {
 
     if (updateOtherPackages) {
       const mismatchFinder: VersionMismatchFinder = VersionMismatchFinder.getMismatches(
-        this._rushConfiguration,
+        this.#rushConfiguration,
         options
       );
-      for (const update of this._getUpdates(mismatchFinder, allDependenciesToUpdate)) {
+      for (const update of this.#getUpdates(mismatchFinder, allDependenciesToUpdate)) {
         this.updateProject(update);
         allPackageUpdates.set(update.project.filePath, update.project);
       }
@@ -229,22 +229,22 @@ export class PackageJsonUpdater {
       async ([filePath, project]) => {
         const modified: boolean = await project.saveIfModifiedAsync();
         if (modified) {
-          this._terminal.writeLine(Colorize.green('Wrote ') + filePath);
+          this.#terminal.writeLine(Colorize.green('Wrote ') + filePath);
         }
       },
       { concurrency: 10 }
     );
 
     if (!skipUpdate) {
-      if (this._rushConfiguration.subspacesFeatureEnabled) {
-        const subspaceSet: ReadonlySet<Subspace> = this._rushConfiguration.getSubspacesForProjects(
+      if (this.#rushConfiguration.subspacesFeatureEnabled) {
+        const subspaceSet: ReadonlySet<Subspace> = this.#rushConfiguration.getSubspacesForProjects(
           options.projects
         );
         for (const subspace of subspaceSet) {
-          await this._doUpdateAsync(debugInstall, subspace, variant);
+          await this.#doUpdateAsync(debugInstall, subspace, variant);
         }
       } else {
-        await this._doUpdateAsync(debugInstall, this._rushConfiguration.defaultSubspace, variant);
+        await this.#doUpdateAsync(debugInstall, this.#rushConfiguration.defaultSubspace, variant);
       }
     }
   }
@@ -252,9 +252,9 @@ export class PackageJsonUpdater {
   public async doRushUpdateAsync(options: IPackageJsonUpdaterRushBaseUpdateOptions): Promise<void> {
     let allPackageUpdates: IUpdateProjectOptions[] = [];
     if (options.actionName === 'add') {
-      allPackageUpdates = await this._doRushAddAsync(options as IPackageJsonUpdaterRushAddOptions);
+      allPackageUpdates = await this.#doRushAddAsync(options as IPackageJsonUpdaterRushAddOptions);
     } else if (options.actionName === 'remove') {
-      allPackageUpdates = await this._doRushRemoveAsync(options as IPackageJsonUpdaterRushRemoveOptions);
+      allPackageUpdates = await this.#doRushRemoveAsync(options as IPackageJsonUpdaterRushRemoveOptions);
     } else {
       throw new Error('only accept "rush add" or "rush remove"');
     }
@@ -265,36 +265,36 @@ export class PackageJsonUpdater {
       async ({ project }) => {
         const modified: boolean = await project.saveIfModifiedAsync();
         if (modified) {
-          this._terminal.writeLine(Colorize.green('Wrote'), project.filePath);
+          this.#terminal.writeLine(Colorize.green('Wrote'), project.filePath);
         }
       },
       { concurrency: 10 }
     );
 
     if (!skipUpdate) {
-      if (this._rushConfiguration.subspacesFeatureEnabled) {
-        const subspaceSet: ReadonlySet<Subspace> = this._rushConfiguration.getSubspacesForProjects(
+      if (this.#rushConfiguration.subspacesFeatureEnabled) {
+        const subspaceSet: ReadonlySet<Subspace> = this.#rushConfiguration.getSubspacesForProjects(
           options.projects
         );
         for (const subspace of subspaceSet) {
-          await this._doUpdateAsync(debugInstall, subspace, variant);
+          await this.#doUpdateAsync(debugInstall, subspace, variant);
         }
       } else {
-        await this._doUpdateAsync(debugInstall, this._rushConfiguration.defaultSubspace, variant);
+        await this.#doUpdateAsync(debugInstall, this.#rushConfiguration.defaultSubspace, variant);
       }
     }
   }
 
-  private async _doUpdateAsync(
+  async #doUpdateAsync(
     debugInstall: boolean,
     subspace: Subspace,
     variant: string | undefined
   ): Promise<void> {
-    this._terminal.writeLine();
-    this._terminal.writeLine(Colorize.green('Running "rush update"'));
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
+    this.#terminal.writeLine(Colorize.green('Running "rush update"'));
+    this.#terminal.writeLine();
 
-    const purgeManager: PurgeManager = new PurgeManager(this._rushConfiguration, this._rushGlobalFolder);
+    const purgeManager: PurgeManager = new PurgeManager(this.#rushConfiguration, this.#rushGlobalFolder);
     const installManagerOptions: IInstallManagerOptions = {
       debug: debugInstall,
       allowShrinkwrapUpdates: true,
@@ -308,15 +308,15 @@ export class PackageJsonUpdater {
       variant,
       maxInstallAttempts: RushConstants.defaultMaxInstallAttempts,
       pnpmFilterArgumentValues: [],
-      selectedProjects: new Set(this._rushConfiguration.projects),
+      selectedProjects: new Set(this.#rushConfiguration.projects),
       checkOnly: false,
       subspace: subspace,
-      terminal: this._terminal
+      terminal: this.#terminal
     };
 
     const installManager: BaseInstallManager = await InstallManagerFactory.getInstallManagerAsync(
-      this._rushConfiguration,
-      this._rushGlobalFolder,
+      this.#rushConfiguration,
+      this.#rushGlobalFolder,
       purgeManager,
       installManagerOptions
     );
@@ -330,7 +330,7 @@ export class PackageJsonUpdater {
   /**
    * Adds a dependency to a particular project. The core business logic for "rush add".
    */
-  private async _doRushAddAsync(
+  async #doRushAddAsync(
     options: IPackageJsonUpdaterRushAddOptions
   ): Promise<IUpdateProjectOptions[]> {
     const { projects } = options;
@@ -340,20 +340,20 @@ export class PackageJsonUpdater {
       './DependencyAnalyzer'
     );
     const dependencyAnalyzer: DependencyAnalyzer = DependencyAnalyzer.forRushConfiguration(
-      this._rushConfiguration
+      this.#rushConfiguration
     );
 
     const allPackageUpdates: IUpdateProjectOptions[] = [];
-    const subspaceSet: ReadonlySet<Subspace> = this._rushConfiguration.getSubspacesForProjects(projects);
+    const subspaceSet: ReadonlySet<Subspace> = this.#rushConfiguration.getSubspacesForProjects(projects);
     for (const subspace of subspaceSet) {
       // Projects for this subspace
-      allPackageUpdates.push(...(await this._updateProjectsAsync(subspace, dependencyAnalyzer, options)));
+      allPackageUpdates.push(...(await this.#updateProjectsAsync(subspace, dependencyAnalyzer, options)));
     }
 
     return allPackageUpdates;
   }
 
-  private async _updateProjectsAsync(
+  async #updateProjectsAsync(
     subspace: Subspace,
     dependencyAnalyzer: DependencyAnalyzer,
     options: IPackageJsonUpdaterRushAddOptions
@@ -372,7 +372,7 @@ export class PackageJsonUpdater {
       commonVersionsConfiguration
     }: IDependencyAnalysis = dependencyAnalyzer.getAnalysis(subspace, variant, options.actionName === 'add');
 
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
     const dependenciesToAddOrUpdate: Record<string, string> = {};
     for (const { packageName, version: initialVersion, rangeStyle } of packagesToUpdate) {
       const implicitlyPreferredVersion: string | undefined =
@@ -381,7 +381,7 @@ export class PackageJsonUpdater {
       const explicitlyPreferredVersion: string | undefined =
         commonVersionsConfiguration.preferredVersions.get(packageName);
 
-      const version: string = await this._getNormalizedVersionSpecAsync(
+      const version: string = await this.#getNormalizedVersionSpecAsync(
         subspaceProjects,
         packageName,
         initialVersion,
@@ -392,12 +392,12 @@ export class PackageJsonUpdater {
       );
 
       dependenciesToAddOrUpdate[packageName] = version;
-      this._terminal.writeLine(
+      this.#terminal.writeLine(
         Colorize.green('Updating projects to use '),
         `${packageName}@`,
         Colorize.cyan(version)
       );
-      this._terminal.writeLine();
+      this.#terminal.writeLine();
 
       const existingSpecifiedVersions: Set<string> | undefined = allVersionsByPackageName.get(packageName);
       if (
@@ -433,13 +433,13 @@ export class PackageJsonUpdater {
       // we need to do a mismatch check
       if (updateOtherPackages) {
         const mismatchFinder: VersionMismatchFinder = VersionMismatchFinder.getMismatches(
-          this._rushConfiguration,
+          this.#rushConfiguration,
           {
             subspace,
             variant
           }
         );
-        otherPackageUpdates = this._getUpdates(mismatchFinder, Object.entries(dependenciesToAddOrUpdate));
+        otherPackageUpdates = this.#getUpdates(mismatchFinder, Object.entries(dependenciesToAddOrUpdate));
       }
 
       this.updateProjects(otherPackageUpdates);
@@ -450,7 +450,7 @@ export class PackageJsonUpdater {
     return allPackageUpdates;
   }
 
-  private _getUpdates(
+  #getUpdates(
     mismatchFinder: VersionMismatchFinder,
     dependenciesToUpdate: Iterable<[string, string]>
   ): IUpdateProjectOptions[] {
@@ -481,12 +481,12 @@ export class PackageJsonUpdater {
   /**
    * Remove a dependency from a particular project. The core business logic for "rush remove".
    */
-  private async _doRushRemoveAsync(
+  async #doRushRemoveAsync(
     options: IPackageJsonUpdaterRushRemoveOptions
   ): Promise<IRemoveProjectOptions[]> {
     const { projects, packagesToUpdate } = options;
 
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
     const dependenciesToRemove: Record<string, string> = {};
 
     const allPackageUpdates: IRemoveProjectOptions[] = [];
@@ -568,7 +568,7 @@ export class PackageJsonUpdater {
    * @param rangeStyle - if this version is selected by querying registry, then this range specifier is prepended to
    *   the selected version.
    */
-  private async _getNormalizedVersionSpecAsync(
+  async #getNormalizedVersionSpecAsync(
     projects: RushConfigurationProject[],
     packageName: string,
     initialSpec: string | undefined,
@@ -577,21 +577,21 @@ export class PackageJsonUpdater {
     rangeStyle: SemVerStyle,
     ensureConsistentVersions: boolean | undefined
   ): Promise<string> {
-    this._terminal.writeLine(Colorize.gray(`Determining new version for dependency: ${packageName}`));
+    this.#terminal.writeLine(Colorize.gray(`Determining new version for dependency: ${packageName}`));
     if (initialSpec) {
-      this._terminal.writeLine(`Specified version selector: ${Colorize.cyan(initialSpec)}`);
+      this.#terminal.writeLine(`Specified version selector: ${Colorize.cyan(initialSpec)}`);
     } else {
-      this._terminal.writeLine(
+      this.#terminal.writeLine(
         `No version selector was specified, so the version will be determined automatically.`
       );
     }
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
 
     // if ensureConsistentVersions => reuse the pinned version
     // else, query the registry and use the latest that satisfies semver spec
     if (initialSpec) {
       if (initialSpec === implicitlyPreferredVersion) {
-        this._terminal.writeLine(
+        this.#terminal.writeLine(
           Colorize.green('Assigning "') +
             Colorize.cyan(initialSpec) +
             Colorize.green(
@@ -602,7 +602,7 @@ export class PackageJsonUpdater {
       }
 
       if (initialSpec === explicitlyPreferredVersion) {
-        this._terminal.writeLine(
+        this.#terminal.writeLine(
           Colorize.green('Assigning "') +
             Colorize.cyan(initialSpec) +
             Colorize.green(
@@ -615,7 +615,7 @@ export class PackageJsonUpdater {
 
     if (ensureConsistentVersions && !initialSpec) {
       if (implicitlyPreferredVersion) {
-        this._terminal.writeLine(
+        this.#terminal.writeLine(
           `Assigning the version "${Colorize.cyan(implicitlyPreferredVersion)}" for "${packageName}" ` +
             'because it is already used by other projects in this repo.'
         );
@@ -623,7 +623,7 @@ export class PackageJsonUpdater {
       }
 
       if (explicitlyPreferredVersion) {
-        this._terminal.writeLine(
+        this.#terminal.writeLine(
           `Assigning the version "${Colorize.cyan(explicitlyPreferredVersion)}" for "${packageName}" ` +
             `because it is the preferred version listed in ${RushConstants.commonVersionsFilename}.`
         );
@@ -632,13 +632,13 @@ export class PackageJsonUpdater {
     }
 
     await InstallHelpers.ensureLocalPackageManagerAsync(
-      this._rushConfiguration,
-      this._rushGlobalFolder,
+      this.#rushConfiguration,
+      this.#rushGlobalFolder,
       RushConstants.defaultMaxInstallAttempts
     );
 
     const useWorkspaces: boolean = !!(
-      this._rushConfiguration.pnpmOptions && this._rushConfiguration.pnpmOptions.useWorkspaces
+      this.#rushConfiguration.pnpmOptions && this.#rushConfiguration.pnpmOptions.useWorkspaces
     );
     const workspacePrefix: string = 'workspace:';
 
@@ -648,7 +648,7 @@ export class PackageJsonUpdater {
     }
 
     // determine if the package is a project in the local repository and if the version exists
-    const localProject: RushConfigurationProject | undefined = this._tryGetLocalProject(
+    const localProject: RushConfigurationProject | undefined = this.#tryGetLocalProject(
       packageName,
       projects
     );
@@ -657,8 +657,8 @@ export class PackageJsonUpdater {
     let selectedVersionPrefix: string = '';
 
     if (initialSpec && initialSpec !== 'latest') {
-      this._terminal.writeLine(Colorize.gray('Finding versions that satisfy the selector: ') + initialSpec);
-      this._terminal.writeLine();
+      this.#terminal.writeLine(Colorize.gray('Finding versions that satisfy the selector: ') + initialSpec);
+      this.#terminal.writeLine();
 
       if (localProject !== undefined) {
         const version: string = localProject.packageJson.version;
@@ -681,34 +681,34 @@ export class PackageJsonUpdater {
           );
         }
       } else {
-        this._terminal.writeLine(`Querying registry for all versions of "${packageName}"...`);
+        this.#terminal.writeLine(`Querying registry for all versions of "${packageName}"...`);
 
         let args: string[];
-        if (this._rushConfiguration.packageManager === 'yarn') {
+        if (this.#rushConfiguration.packageManager === 'yarn') {
           args = ['info', packageName, 'versions', '--json'];
         } else {
           args = ['view', packageName, 'versions', '--json'];
         }
 
         const allVersions: string = await Utilities.executeCommandAndCaptureOutputAsync({
-          command: this._rushConfiguration.packageManagerToolFilename,
+          command: this.#rushConfiguration.packageManagerToolFilename,
           args,
-          workingDirectory: this._rushConfiguration.commonTempFolder
+          workingDirectory: this.#rushConfiguration.commonTempFolder
         });
 
         let versionList: string[];
-        if (this._rushConfiguration.packageManager === 'yarn') {
+        if (this.#rushConfiguration.packageManager === 'yarn') {
           versionList = JSON.parse(allVersions).data;
         } else {
           versionList = JSON.parse(allVersions);
         }
 
-        this._terminal.writeLine(Colorize.gray(`Found ${versionList.length} available versions.`));
+        this.#terminal.writeLine(Colorize.gray(`Found ${versionList.length} available versions.`));
 
         for (const version of versionList) {
           if (semver.satisfies(version, initialSpec)) {
             selectedVersion = initialSpec;
-            this._terminal.writeLine(
+            this.#terminal.writeLine(
               `Found a version that satisfies ${initialSpec}: ${Colorize.cyan(version)}`
             );
             break;
@@ -733,19 +733,19 @@ export class PackageJsonUpdater {
           selectedVersion = localProject.packageJson.version;
         }
       } else {
-        if (!this._rushConfiguration.ensureConsistentVersions) {
-          this._terminal.writeLine(
+        if (!this.#rushConfiguration.ensureConsistentVersions) {
+          this.#terminal.writeLine(
             Colorize.gray(
               `The "ensureConsistentVersions" policy is NOT active, so we will assign the latest version.`
             )
           );
-          this._terminal.writeLine();
+          this.#terminal.writeLine();
         }
 
-        this._terminal.writeLine(`Querying NPM registry for latest version of "${packageName}"...`);
+        this.#terminal.writeLine(`Querying NPM registry for latest version of "${packageName}"...`);
 
         let args: string[];
-        if (this._rushConfiguration.packageManager === 'yarn') {
+        if (this.#rushConfiguration.packageManager === 'yarn') {
           args = ['info', packageName, 'dist-tags.latest', '--silent'];
         } else {
           args = ['view', `${packageName}@latest`, 'version'];
@@ -753,19 +753,19 @@ export class PackageJsonUpdater {
 
         selectedVersion = (
           await Utilities.executeCommandAndCaptureOutputAsync({
-            command: this._rushConfiguration.packageManagerToolFilename,
+            command: this.#rushConfiguration.packageManagerToolFilename,
             args,
-            workingDirectory: this._rushConfiguration.commonTempFolder
+            workingDirectory: this.#rushConfiguration.commonTempFolder
           })
         ).trim();
       }
 
-      this._terminal.writeLine();
+      this.#terminal.writeLine();
 
-      this._terminal.writeLine(`Found latest version: ${Colorize.cyan(selectedVersion)}`);
+      this.#terminal.writeLine(`Found latest version: ${Colorize.cyan(selectedVersion)}`);
     }
 
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
 
     let reasonForModification: string = '';
     if (selectedVersion !== '*') {
@@ -797,13 +797,13 @@ export class PackageJsonUpdater {
     }
 
     const normalizedVersion: string = selectedVersionPrefix + selectedVersion;
-    this._terminal.writeLine(
+    this.#terminal.writeLine(
       Colorize.gray(`Assigning version "${normalizedVersion}" for "${packageName}"${reasonForModification}.`)
     );
     return normalizedVersion;
   }
 
-  private _collectAllDownstreamDependencies(
+  #collectAllDownstreamDependencies(
     project: RushConfigurationProject
   ): Set<RushConfigurationProject> {
     const allProjectDownstreamDependencies: Set<RushConfigurationProject> =
@@ -814,7 +814,7 @@ export class PackageJsonUpdater {
     ) => {
       for (const downstreamDependencyProject of rushProject.downstreamDependencyProjects) {
         const foundProject: RushConfigurationProject | undefined =
-          this._rushConfiguration.projectsByName.get(downstreamDependencyProject);
+          this.#rushConfiguration.projectsByName.get(downstreamDependencyProject);
 
         if (!foundProject) {
           continue;
@@ -843,12 +843,12 @@ export class PackageJsonUpdater {
    * This function throws an error if adding the discovered local project as a dependency
    * would create a dependency cycle, or if it would be added to multiple projects.
    */
-  private _tryGetLocalProject(
+  #tryGetLocalProject(
     packageName: string,
     projects: RushConfigurationProject[]
   ): RushConfigurationProject | undefined {
     const foundProject: RushConfigurationProject | undefined =
-      this._rushConfiguration.projectsByName.get(packageName);
+      this.#rushConfiguration.projectsByName.get(packageName);
 
     if (foundProject === undefined) {
       return undefined;
@@ -877,7 +877,7 @@ export class PackageJsonUpdater {
 
     // Are we attempting to create a cycle?
     const downstreamDependencies: Set<RushConfigurationProject> =
-      this._collectAllDownstreamDependencies(project);
+      this.#collectAllDownstreamDependencies(project);
     if (downstreamDependencies.has(foundProject)) {
       throw new Error(
         `Adding "${foundProject.packageName}" as a direct or indirect dependency of ` +
@@ -888,7 +888,7 @@ export class PackageJsonUpdater {
     return foundProject;
   }
 
-  private _cheaplyDetectSemVerRangeStyle(version: string): SemVerStyle {
+  #cheaplyDetectSemVerRangeStyle(version: string): SemVerStyle {
     // create a swtich statement to detect the first character of the version string and determine the range style
     // TODO: This is a temporary solution until we have a better way to detect more complext range styles
     // TODO: Should we handle/care about peerDependencies?
@@ -898,19 +898,19 @@ export class PackageJsonUpdater {
       case '^':
         return SemVerStyle.Caret;
       default:
-        this._terminal.writeLine(
+        this.#terminal.writeLine(
           `No SemVer range detected for version: ${version}. The exact version will be set in package.json.`
         );
         return SemVerStyle.Exact;
     }
   }
 
-  private _normalizeDepsToUpgrade(deps: INpmCheckPackageSummary[]): IPackageForRushAdd[] {
+  #normalizeDepsToUpgrade(deps: INpmCheckPackageSummary[]): IPackageForRushAdd[] {
     return deps.map((dep) => {
       return {
         packageName: dep.moduleName,
         version: dep.latest,
-        rangeStyle: this._cheaplyDetectSemVerRangeStyle(dep.packageJson)
+        rangeStyle: this.#cheaplyDetectSemVerRangeStyle(dep.packageJson)
       };
     });
   }
diff --git a/libraries/rush-lib/src/logic/PackageLookup.ts b/libraries/rush-lib/src/logic/PackageLookup.ts
index 9b0253fc30c..79fdc36d2fa 100644
--- a/libraries/rush-lib/src/logic/PackageLookup.ts
+++ b/libraries/rush-lib/src/logic/PackageLookup.ts
@@ -4,10 +4,10 @@
 import type { BasePackage } from './base/BasePackage';
 
 export class PackageLookup {
-  private _packageMap: Map<string, BasePackage>;
+  #packageMap: Map<string, BasePackage>;
 
   public constructor() {
-    this._packageMap = new Map<string, BasePackage>();
+    this.#packageMap = new Map<string, BasePackage>();
   }
 
   public loadTree(root: BasePackage): void {
@@ -28,13 +28,13 @@ export class PackageLookup {
 
       const key: string = current.nameAndVersion;
 
-      if (!this._packageMap.has(key)) {
-        this._packageMap.set(key, current);
+      if (!this.#packageMap.has(key)) {
+        this.#packageMap.set(key, current);
       }
     }
   }
 
   public getPackage(nameAndVersion: string): BasePackage | undefined {
-    return this._packageMap.get(nameAndVersion);
+    return this.#packageMap.get(nameAndVersion);
   }
 }
diff --git a/libraries/rush-lib/src/logic/PrereleaseToken.ts b/libraries/rush-lib/src/logic/PrereleaseToken.ts
index 3e564f6bcd2..0da8f1df1b7 100644
--- a/libraries/rush-lib/src/logic/PrereleaseToken.ts
+++ b/libraries/rush-lib/src/logic/PrereleaseToken.ts
@@ -2,9 +2,9 @@
 // See LICENSE in the project root for license information.
 
 export class PrereleaseToken {
-  private _prereleaseName: string | undefined;
-  private _suffixName: string | undefined;
-  private _partialPrerelease: boolean;
+  #prereleaseName: string | undefined;
+  #suffixName: string | undefined;
+  #partialPrerelease: boolean;
 
   public readonly name: string;
 
@@ -13,24 +13,24 @@ export class PrereleaseToken {
       throw new Error('Pre-release name and suffix cannot be provided at the same time.');
     }
     this.name = prereleaseName! || suffixName!;
-    this._prereleaseName = prereleaseName;
-    this._suffixName = suffixName;
-    this._partialPrerelease = partialPrerelease;
+    this.#prereleaseName = prereleaseName;
+    this.#suffixName = suffixName;
+    this.#partialPrerelease = partialPrerelease;
   }
 
   public get hasValue(): boolean {
-    return !!this._prereleaseName || !!this._suffixName;
+    return !!this.#prereleaseName || !!this.#suffixName;
   }
 
   public get isPrerelease(): boolean {
-    return !!this._prereleaseName;
+    return !!this.#prereleaseName;
   }
 
   public get isSuffix(): boolean {
-    return !!this._suffixName;
+    return !!this.#suffixName;
   }
 
   public get isPartialPrerelease(): boolean {
-    return this.isPrerelease && this._partialPrerelease;
+    return this.isPrerelease && this.#partialPrerelease;
   }
 }
diff --git a/libraries/rush-lib/src/logic/ProjectChangeAnalyzer.ts b/libraries/rush-lib/src/logic/ProjectChangeAnalyzer.ts
index 3dc0fc6ed25..816a3cc51d7 100644
--- a/libraries/rush-lib/src/logic/ProjectChangeAnalyzer.ts
+++ b/libraries/rush-lib/src/logic/ProjectChangeAnalyzer.ts
@@ -77,12 +77,12 @@ export interface IRawRepoState {
  * @beta
  */
 export class ProjectChangeAnalyzer {
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _git: Git;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #git: Git;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
-    this._git = new Git(this._rushConfiguration);
+    this.#rushConfiguration = rushConfiguration;
+    this.#git = new Git(this.#rushConfiguration);
   }
 
   /**
@@ -93,7 +93,7 @@ export class ProjectChangeAnalyzer {
   public async getChangedProjectsAsync(
     options: IGetChangedProjectsOptions
   ): Promise<Set<RushConfigurationProject>> {
-    const { _rushConfiguration: rushConfiguration } = this;
+    const rushConfiguration: RushConfiguration = this.#rushConfiguration;
 
     const {
       targetBranchName,
@@ -105,14 +105,14 @@ export class ProjectChangeAnalyzer {
       excludeVersionOnlyChanges
     } = options;
 
-    const gitPath: string = this._git.getGitPathOrThrow();
+    const gitPath: string = this.#git.getGitPathOrThrow();
     const repoRoot: string = getRepoRoot(rushConfiguration.rushJsonFolder);
 
     // if the given targetBranchName is a commit, we assume it is the merge base
-    const isTargetBranchACommit: boolean = await this._git.determineIfRefIsACommitAsync(targetBranchName);
+    const isTargetBranchACommit: boolean = await this.#git.determineIfRefIsACommitAsync(targetBranchName);
     const mergeCommit: string = isTargetBranchACommit
       ? targetBranchName
-      : await this._git.getMergeBaseAsync(targetBranchName, terminal, shouldFetch);
+      : await this.#git.getMergeBaseAsync(targetBranchName, terminal, shouldFetch);
 
     const changedFiles: Map<string, IFileDiffStatus> = getRepoChanges(repoRoot, mergeCommit, gitPath);
     const lookup: LookupByPath<RushConfigurationProject> =
@@ -165,7 +165,7 @@ export class ProjectChangeAnalyzer {
             const isVersionOnlyChange: boolean = await isVersionOnlyChangeAsync(
               diffStatus,
               repoRoot,
-              this._git
+              this.#git
             );
             if (isVersionOnlyChange) {
               continue; // Skip version-only package.json changes
@@ -186,7 +186,7 @@ export class ProjectChangeAnalyzer {
       : [rushConfiguration.defaultSubspace];
 
     const variantToUse: string | undefined = includeExternalDependencies
-      ? (variant ?? (await this._rushConfiguration.getCurrentlyInstalledVariantAsync()))
+      ? (variant ?? (await this.#rushConfiguration.getCurrentlyInstalledVariantAsync()))
       : undefined;
 
     await Async.forEachAsync(subspaces, async (subspace: Subspace) => {
@@ -194,7 +194,7 @@ export class ProjectChangeAnalyzer {
 
       // Detect changes to pnpm catalog entries in pnpm-config.json
       if (rushConfiguration.isPnpm) {
-        await this._detectCatalogChangesAsync(
+        await this.#detectCatalogChangesAsync(
           subspace,
           rushConfiguration,
           changedFiles,
@@ -245,7 +245,7 @@ export class ProjectChangeAnalyzer {
               throw new Error(`Unable to obtain current shrinkwrap file.`);
             }
 
-            const oldShrinkwrapText: string = await this._git.getBlobContentAsync({
+            const oldShrinkwrapText: string = await this.#git.getBlobContentAsync({
               // <ref>:<path> syntax: https://git-scm.com/docs/gitrevisions
               blobSpec: `${mergeCommit}:${relativeShrinkwrapFilePath}`,
               repositoryRoot: repoRoot
@@ -305,9 +305,9 @@ export class ProjectChangeAnalyzer {
     projectSelection?: ReadonlySet<RushConfigurationProject>
   ): Promise<GetInputsSnapshotAsyncFn | undefined> {
     try {
-      const gitPath: string = this._git.getGitPathOrThrow();
+      const gitPath: string = this.#git.getGitPathOrThrow();
 
-      if (!this._git.isPathUnderGitWorkingTree()) {
+      if (!this.#git.isPathUnderGitWorkingTree()) {
         terminal.writeLine(
           `The Rush monorepo is not in a Git repository. Rush will proceed without incremental build support.`
         );
@@ -315,7 +315,7 @@ export class ProjectChangeAnalyzer {
         return;
       }
 
-      const rushConfiguration: RushConfiguration = this._rushConfiguration;
+      const rushConfiguration: RushConfiguration = this.#rushConfiguration;
 
       // Do not use getGitInfo().root; it is the root of the *primary* worktree, not the *current* one.
       const rootDirectory: string = getRepoRoot(rushConfiguration.rushJsonFolder, gitPath);
@@ -379,7 +379,7 @@ export class ProjectChangeAnalyzer {
       } else {
         // Add the shrinkwrap file to every project's dependencies
         const currentVariant: string | undefined =
-          await this._rushConfiguration.getCurrentlyInstalledVariantAsync();
+          await this.#rushConfiguration.getCurrentlyInstalledVariantAsync();
 
         const shrinkwrapFile: string = Path.convertToSlashes(
           path.relative(
@@ -392,14 +392,14 @@ export class ProjectChangeAnalyzer {
       }
 
       const lookupByPath: IReadonlyLookupByPath<RushConfigurationProject> =
-        this._rushConfiguration.getProjectLookupForRoot(rootDirectory);
+        this.#rushConfiguration.getProjectLookupForRoot(rootDirectory);
 
       let filterPath: string[] = [];
 
       if (
         projectSelection &&
         projectSelection.size > 0 &&
-        this._rushConfiguration.experimentsConfiguration.configuration.enableSubpathScan
+        this.#rushConfiguration.experimentsConfiguration.configuration.enableSubpathScan
       ) {
         filterPath = Array.from(projectSelection, ({ projectFolder }) => projectFolder);
       }
@@ -476,7 +476,7 @@ export class ProjectChangeAnalyzer {
     rootDir: string,
     terminal: ITerminal
   ): Promise<Map<string, T>> {
-    const ignoreMatcher: Ignore | undefined = await this._getIgnoreMatcherForProjectAsync(project, terminal);
+    const ignoreMatcher: Ignore | undefined = await this.#getIgnoreMatcherForProjectAsync(project, terminal);
     if (!ignoreMatcher) {
       return unfilteredProjectData;
     }
@@ -498,7 +498,7 @@ export class ProjectChangeAnalyzer {
     return filteredProjectData;
   }
 
-  private async _getIgnoreMatcherForProjectAsync(
+  async #getIgnoreMatcherForProjectAsync(
     project: RushConfigurationProject,
     terminal: ITerminal
   ): Promise<Ignore | undefined> {
@@ -516,7 +516,7 @@ export class ProjectChangeAnalyzer {
    * Detects changes to pnpm catalog entries in a subspace's pnpm-config.json and marks
    * affected projects as changed.
    */
-  private async _detectCatalogChangesAsync(
+  async #detectCatalogChangesAsync(
     subspace: Subspace,
     rushConfiguration: RushConfiguration,
     changedFiles: Map<string, IFileDiffStatus>,
@@ -541,7 +541,7 @@ export class ProjectChangeAnalyzer {
     // Maps catalogNamespace (e.g. "default", "react17") → Set of changed package names
     let oldCatalogs: Record<string, Record<string, string>> | undefined;
     try {
-      const oldPnpmConfigText: string = await this._git.getBlobContentAsync({
+      const oldPnpmConfigText: string = await this.#git.getBlobContentAsync({
         blobSpec: `${mergeCommit}:${pnpmConfigRelativePath}`,
         repositoryRoot: repoRoot
       });
diff --git a/libraries/rush-lib/src/logic/ProjectCommandSet.ts b/libraries/rush-lib/src/logic/ProjectCommandSet.ts
index 1070f31b5f8..d7e111d6522 100644
--- a/libraries/rush-lib/src/logic/ProjectCommandSet.ts
+++ b/libraries/rush-lib/src/logic/ProjectCommandSet.ts
@@ -9,7 +9,7 @@ import type { IPackageJson, IPackageJsonScriptTable } from '@rushstack/node-core
 export class ProjectCommandSet {
   public readonly malformedScriptNames: string[] = [];
   public readonly commandNames: string[] = [];
-  private readonly _scriptsByName: Map<string, string> = new Map<string, string>();
+  readonly #scriptsByName: Map<string, string> = new Map<string, string>();
 
   public constructor(packageJson: IPackageJson) {
     const scripts: IPackageJsonScriptTable = packageJson.scripts || {};
@@ -19,7 +19,7 @@ export class ProjectCommandSet {
         this.malformedScriptNames.push(scriptName);
       } else {
         this.commandNames.push(scriptName);
-        this._scriptsByName.set(scriptName, scripts[scriptName]);
+        this.#scriptsByName.set(scriptName, scripts[scriptName]);
       }
     }
 
@@ -27,7 +27,7 @@ export class ProjectCommandSet {
   }
 
   public tryGetScriptBody(commandName: string): string | undefined {
-    return this._scriptsByName.get(commandName);
+    return this.#scriptsByName.get(commandName);
   }
 
   public getScriptBody(commandName: string): string {
diff --git a/libraries/rush-lib/src/logic/ProjectImpactGraphGenerator.ts b/libraries/rush-lib/src/logic/ProjectImpactGraphGenerator.ts
index 5f23e9d6339..594dffa2450 100644
--- a/libraries/rush-lib/src/logic/ProjectImpactGraphGenerator.ts
+++ b/libraries/rush-lib/src/logic/ProjectImpactGraphGenerator.ts
@@ -50,39 +50,39 @@ async function tryReadFileLinesAsync(filePath: string): Promise<string[] | undef
 }
 
 export class ProjectImpactGraphGenerator {
-  private readonly _terminal: ITerminal;
+  readonly #terminal: ITerminal;
 
   /**
    * The Rush configuration
    */
-  private readonly _rushConfiguration: RushConfiguration;
+  readonly #rushConfiguration: RushConfiguration;
 
   /**
    * Full path of repository root
    */
-  private readonly _repositoryRoot: string;
+  readonly #repositoryRoot: string;
 
   /**
    * Full path to `project-impact-graph.yaml`
    */
-  private readonly _projectImpactGraphFilePath: string;
+  readonly #projectImpactGraphFilePath: string;
 
   /**
    * Get repositoryRoot and load projects within the rush.json
    */
   public constructor(terminal: ITerminal, rushConfiguration: RushConfiguration) {
-    this._terminal = terminal;
-    this._rushConfiguration = rushConfiguration;
+    this.#terminal = terminal;
+    this.#rushConfiguration = rushConfiguration;
     const { rushJsonFolder } = rushConfiguration;
-    this._repositoryRoot = rushJsonFolder;
-    this._projectImpactGraphFilePath = `${rushJsonFolder}/${RushConstants.projectImpactGraphFilename}`;
+    this.#repositoryRoot = rushJsonFolder;
+    this.#projectImpactGraphFilePath = `${rushJsonFolder}/${RushConstants.projectImpactGraphFilename}`;
   }
 
   /**
    * Load global excluded globs
    */
-  private async _loadGlobalExcludedGlobsAsync(): Promise<string[] | undefined> {
-    const filePath: string = `${this._repositoryRoot}/${RushConstants.mergeQueueIgnoreFileName}`;
+  async #loadGlobalExcludedGlobsAsync(): Promise<string[] | undefined> {
+    const filePath: string = `${this.#repositoryRoot}/${RushConstants.mergeQueueIgnoreFileName}`;
     return await tryReadFileLinesAsync(filePath);
   }
 
@@ -90,10 +90,10 @@ export class ProjectImpactGraphGenerator {
    * Load project excluded globs
    * @param projectRootRelativePath - project root relative path
    */
-  private async _tryLoadProjectExcludedGlobsAsync(
+  async #tryLoadProjectExcludedGlobsAsync(
     projectRootRelativePath: string
   ): Promise<string[] | undefined> {
-    const filePath: string = `${this._repositoryRoot}/${projectRootRelativePath}/${RushConstants.mergeQueueIgnoreFileName}`;
+    const filePath: string = `${this.#repositoryRoot}/${projectRootRelativePath}/${RushConstants.mergeQueueIgnoreFileName}`;
 
     const globs: string[] | undefined = await tryReadFileLinesAsync(filePath);
     if (globs) {
@@ -112,9 +112,9 @@ export class ProjectImpactGraphGenerator {
     const stopwatch: Stopwatch = Stopwatch.start();
 
     const [globalExcludedGlobs = DEFAULT_GLOBAL_EXCLUDED_GLOBS, projectEntries] = await Promise.all([
-      this._loadGlobalExcludedGlobsAsync(),
+      this.#loadGlobalExcludedGlobsAsync(),
       Async.mapAsync<RushConfigurationProject, [string, IProjectImpactGraphProjectConfiguration]>(
-        this._rushConfiguration.projects,
+        this.#rushConfiguration.projects,
         async ({ packageName, consumingProjects, projectRelativeFolder }) => {
           const dependentList: string[] = [packageName];
           for (const consumingProject of consumingProjects) {
@@ -127,7 +127,7 @@ export class ProjectImpactGraphGenerator {
           };
 
           const projectExcludedGlobs: string[] | undefined =
-            await this._tryLoadProjectExcludedGlobsAsync(projectRelativeFolder);
+            await this.#tryLoadProjectExcludedGlobsAsync(projectRelativeFolder);
           if (projectExcludedGlobs) {
             projectImpactGraphProjectConfiguration.excludedGlobs = projectExcludedGlobs;
           }
@@ -142,17 +142,17 @@ export class ProjectImpactGraphGenerator {
     const projects: Record<string, IProjectImpactGraphProjectConfiguration> =
       Object.fromEntries(projectEntries);
     const content: IProjectImpactGraphFile = { globalExcludedGlobs, projects };
-    await FileSystem.writeFileAsync(this._projectImpactGraphFilePath, yaml.dump(content));
+    await FileSystem.writeFileAsync(this.#projectImpactGraphFilePath, yaml.dump(content));
 
     stopwatch.stop();
-    this._terminal.writeLine();
-    this._terminal.writeLine(
+    this.#terminal.writeLine();
+    this.#terminal.writeLine(
       Colorize.green(`Generate project impact graph successfully. (${stopwatch.toString()})`)
     );
   }
 
   public async validateAsync(): Promise<boolean> {
     // TODO: More validation other than just existence
-    return await FileSystem.existsAsync(this._projectImpactGraphFilePath);
+    return await FileSystem.existsAsync(this.#projectImpactGraphFilePath);
   }
 }
diff --git a/libraries/rush-lib/src/logic/ProjectWatcher.ts b/libraries/rush-lib/src/logic/ProjectWatcher.ts
index 0e0c9adb877..73010daed04 100644
--- a/libraries/rush-lib/src/logic/ProjectWatcher.ts
+++ b/libraries/rush-lib/src/logic/ProjectWatcher.ts
@@ -66,36 +66,36 @@ const KEYBIND_HELP: string =
  * signal is needed; actual change detection is deferred to `getInputsSnapshotAsync`.
  */
 export class ProjectWatcher {
-  private readonly _debounceMs: number;
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _terminal: ITerminal;
-  private readonly _graph: IOperationGraph;
-
-  private _repoRoot: string | undefined;
-  private _watchers: Map<string, fs.FSWatcher> | undefined;
-  private _closePromises: Promise<void>[] = [];
-  private _debounceHandle: NodeJS.Timeout | undefined;
-  private _isWatching: boolean = false;
-  private _lastStatus: string | undefined;
-  private _renderedStatusLines: number = 0;
-  private _lastSnapshot: IInputsSnapshot | undefined;
-  private _stdinListening: boolean = false;
-  private _stdinHadRawMode: boolean | undefined;
-  private _onStdinDataBound: ((chunk: Buffer | string) => void) | undefined;
+  readonly #debounceMs: number;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #terminal: ITerminal;
+  readonly #graph: IOperationGraph;
+
+  #repoRoot: string | undefined;
+  #watchers: Map<string, fs.FSWatcher> | undefined;
+  #closePromises: Promise<void>[] = [];
+  #debounceHandle: NodeJS.Timeout | undefined;
+  #isWatching: boolean = false;
+  #lastStatus: string | undefined;
+  #renderedStatusLines: number = 0;
+  #lastSnapshot: IInputsSnapshot | undefined;
+  #stdinListening: boolean = false;
+  #stdinHadRawMode: boolean | undefined;
+  #onStdinDataBound: ((chunk: Buffer | string) => void) | undefined;
 
   public constructor(options: IProjectWatcherOptions) {
     const { graph, debounceMs, rushConfiguration, terminal, initialSnapshot } = options;
-    this._graph = graph;
-    this._debounceMs = debounceMs;
-    this._rushConfiguration = rushConfiguration;
-    this._terminal = terminal;
-    this._lastSnapshot = initialSnapshot; // Seed snapshot
+    this.#graph = graph;
+    this.#debounceMs = debounceMs;
+    this.#rushConfiguration = rushConfiguration;
+    this.#terminal = terminal;
+    this.#lastSnapshot = initialSnapshot; // Seed snapshot
 
     const gitPath: string = new Git(rushConfiguration).getGitPathOrThrow();
-    this._repoRoot = Path.convertToSlashes(getRepoRoot(rushConfiguration.rushJsonFolder, gitPath));
+    this.#repoRoot = Path.convertToSlashes(getRepoRoot(rushConfiguration.rushJsonFolder, gitPath));
 
     // Initialize stdin listener early so keybinds are available immediately
-    this._ensureStdin();
+    this.#ensureStdin();
 
     // Capture snapshot (if provided) prior to executing next iteration (will replace initial snapshot)
     graph.hooks.beforeExecuteIterationAsync.tapPromise(
@@ -105,21 +105,21 @@ export class ProjectWatcher {
         iterationOptions: IOperationGraphIterationOptions
       ): Promise<void> => {
         this.clearStatus();
-        this._lastSnapshot = iterationOptions.inputsSnapshot;
-        await this._stopWatchingAsync();
+        this.#lastSnapshot = iterationOptions.inputsSnapshot;
+        await this.#stopWatchingAsync();
       }
     );
 
     // Start watching once execution loop enters waiting state
     graph.hooks.onIdle.tap('ProjectWatcher', () => {
-      this._startWatching();
+      this.#startWatching();
     });
 
     // Dispose stdin listener when session aborts
     graph.abortController.signal.addEventListener(
       'abort',
       () => {
-        this._disposeStdin();
+        this.#disposeStdin();
       },
       { once: true }
     );
@@ -130,14 +130,14 @@ export class ProjectWatcher {
    * to overwrite previously rendered lines.
    */
   public clearStatus(): void {
-    this._renderedStatusLines = 0;
+    this.#renderedStatusLines = 0;
   }
 
   /**
    * Re-renders the most recent status line (or a default) in place.
    */
   public rerenderStatus(): void {
-    this._setStatus(this._lastStatus ?? 'Waiting for changes...');
+    this.#setStatus(this.#lastStatus ?? 'Waiting for changes...');
   }
 
   /**
@@ -145,14 +145,14 @@ export class ProjectWatcher {
    * and keybind help when stdin is active. Overwrites previously rendered status lines
    * when not mid-execution.
    */
-  private _setStatus(status: string): void {
-    const graph: IOperationGraph = this._graph;
+  #setStatus(status: string): void {
+    const graph: IOperationGraph = this.#graph;
     const isPaused: boolean = graph.pauseNextIteration === true;
     const hasScheduledIteration: boolean = graph.hasScheduledIteration;
     const modeLabel: string = isPaused ? 'PAUSED' : 'WATCHING';
     const pendingLabel: string = hasScheduledIteration ? ' PENDING' : '';
     const statusLines: string[] = [`[${modeLabel}${pendingLabel}] Watch Status: ${status}`];
-    if (this._stdinListening) {
+    if (this.#stdinListening) {
       const lines: string[] = [];
       // First line: modes
       lines.push(
@@ -164,15 +164,15 @@ export class ProjectWatcher {
     }
     if (graph.status !== OperationStatus.Executing) {
       // If rendering during execution, don't try to clean previous output.
-      if (this._renderedStatusLines > 0) {
+      if (this.#renderedStatusLines > 0) {
         readline.cursorTo(process.stdout, 0);
-        readline.moveCursor(process.stdout, 0, -this._renderedStatusLines);
+        readline.moveCursor(process.stdout, 0, -this.#renderedStatusLines);
         readline.clearScreenDown(process.stdout);
       }
-      this._renderedStatusLines = statusLines.length;
+      this.#renderedStatusLines = statusLines.length;
     }
-    this._lastStatus = status;
-    this._terminal.writeLine(Colorize.bold(Colorize.cyan(statusLines.join('\n'))));
+    this.#lastStatus = status;
+    this.#terminal.writeLine(Colorize.bold(Colorize.cyan(statusLines.join('\n'))));
   }
 
   /**
@@ -180,15 +180,15 @@ export class ProjectWatcher {
    * On platforms without native recursive watch support (Linux), enumerates nested
    * folders from the last snapshot to set up individual watchers.
    */
-  private _startWatching(): void {
-    if (this._isWatching) {
+  #startWatching(): void {
+    if (this.#isWatching) {
       return;
     }
-    this._isWatching = true;
-    const sessionAbortSignal: AbortSignal = this._graph.abortController.signal;
-    const repoRoot: string = Path.convertToSlashes(this._rushConfiguration.rushJsonFolder);
+    this.#isWatching = true;
+    const sessionAbortSignal: AbortSignal = this.#graph.abortController.signal;
+    const repoRoot: string = Path.convertToSlashes(this.#rushConfiguration.rushJsonFolder);
     const useNativeRecursiveWatch: boolean = os.platform() === 'win32' || os.platform() === 'darwin';
-    const operations: ReadonlySet<Operation> = this._graph.operations;
+    const operations: ReadonlySet<Operation> = this.#graph.operations;
 
     const projectFolders: Set<string> = new Set();
     for (const op of operations) {
@@ -197,17 +197,17 @@ export class ProjectWatcher {
 
     // Derive nested folder list if on Linux (no native recursive) and snapshot available
     let foldersToWatch: Set<string> = new Set();
-    if (!useNativeRecursiveWatch && this._lastSnapshot) {
+    if (!useNativeRecursiveWatch && this.#lastSnapshot) {
       for (const op of operations) {
         const { associatedProject: rushProject } = op;
         const tracked: ReadonlyMap<string, string> | undefined =
-          this._lastSnapshot.getTrackedFileHashesForOperation(rushProject);
+          this.#lastSnapshot.getTrackedFileHashesForOperation(rushProject);
         if (!tracked) {
           continue;
         }
         const prefixLength: number = rushProject.projectFolder.length - repoRoot.length - 1;
         for (const relPrefix of _enumeratePathsToWatch(tracked.keys(), prefixLength)) {
-          foldersToWatch.add(`${this._repoRoot}/${relPrefix}`);
+          foldersToWatch.add(`${this.#repoRoot}/${relPrefix}`);
         }
       }
     }
@@ -216,7 +216,7 @@ export class ProjectWatcher {
       foldersToWatch = projectFolders;
     }
 
-    const watchers: Map<string, fs.FSWatcher> = (this._watchers = new Map());
+    const watchers: Map<string, fs.FSWatcher> = (this.#watchers = new Map());
 
     const addWatcher = (watchedPath: string, recursive: boolean): void => {
       if (watchers.has(watchedPath)) {
@@ -230,10 +230,10 @@ export class ProjectWatcher {
             recursive: recursive && useNativeRecursiveWatch,
             signal: sessionAbortSignal
           },
-          (eventType, fileName) => this._onFsEvent(fileName)
+          (eventType, fileName) => this.#onFsEvent(fileName)
         );
         watchers.set(watchedPath, watcher);
-        this._closePromises.push(
+        this.#closePromises.push(
           once(watcher, 'close').then(() => {
             watchers.delete(watchedPath);
             watcher.removeAllListeners();
@@ -241,13 +241,13 @@ export class ProjectWatcher {
           })
         );
       } catch (e) {
-        this._terminal.writeDebugLine(`Failed to watch path ${watchedPath}: ${(e as Error).message}`);
+        this.#terminal.writeDebugLine(`Failed to watch path ${watchedPath}: ${(e as Error).message}`);
       }
     };
 
     // Always watch repo root and common config
     addWatcher(repoRoot, false);
-    addWatcher(Path.convertToSlashes(this._rushConfiguration.commonRushConfigFolder), false);
+    addWatcher(Path.convertToSlashes(this.#rushConfiguration.commonRushConfigFolder), false);
     if (useNativeRecursiveWatch) {
       for (const folder of projectFolders) {
         addWatcher(folder, true);
@@ -257,55 +257,56 @@ export class ProjectWatcher {
         addWatcher(folder, true);
       }
     }
-    this._setStatus('Waiting for changes...');
+    this.#setStatus('Waiting for changes...');
   }
 
   /**
    * Closes all active file system watchers and waits for their close events to settle.
    */
-  private async _stopWatchingAsync(): Promise<void> {
-    if (!this._isWatching) {
+  async #stopWatchingAsync(): Promise<void> {
+    if (!this.#isWatching) {
       return;
     }
-    this._isWatching = false;
-    if (this._debounceHandle) {
-      clearTimeout(this._debounceHandle);
-      this._debounceHandle = undefined;
+    this.#isWatching = false;
+    if (this.#debounceHandle) {
+      clearTimeout(this.#debounceHandle);
+      this.#debounceHandle = undefined;
     }
-    if (this._watchers) {
-      for (const watcher of this._watchers.values()) {
+    if (this.#watchers) {
+      for (const watcher of this.#watchers.values()) {
         watcher.close();
       }
     }
-    await Promise.all(this._closePromises);
-    this._closePromises = [];
-    this._watchers = undefined;
-    this._terminal.writeDebugLine('ProjectWatcher: watchers stopped');
+    await Promise.all(this.#closePromises);
+    this.#closePromises = [];
+    this.#watchers = undefined;
+    this.#terminal.writeDebugLine('ProjectWatcher: watchers stopped');
   }
 
   /**
    * Handles a raw file system event by debouncing and scheduling an iteration.
    * Ignores changes to `.git` and `node_modules`.
    */
-  private _onFsEvent(fileName: string | null): void {
+  // eslint-disable-next-line @rushstack/no-new-null -- The decoupled ESLint plugin does not recognize native private methods yet.
+  #onFsEvent(fileName: string | null): void {
     if (fileName === '.git' || fileName === 'node_modules') {
       return;
     }
-    if (this._debounceHandle) {
-      clearTimeout(this._debounceHandle);
+    if (this.#debounceHandle) {
+      clearTimeout(this.#debounceHandle);
     }
-    this._debounceHandle = setTimeout(() => this._scheduleIteration(), this._debounceMs);
+    this.#debounceHandle = setTimeout(() => this.#scheduleIteration(), this.#debounceMs);
   }
 
   /**
    * Schedules a new execution iteration on the graph in response to detected file changes.
    */
-  private _scheduleIteration(): void {
-    this._setStatus('File change detected. Queuing new iteration...');
-    this._graph
+  #scheduleIteration(): void {
+    this.#setStatus('File change detected. Queuing new iteration...');
+    this.#graph
       .scheduleIterationAsync({})
       .catch((e: unknown) =>
-        this._terminal.writeErrorLine(`Failed to queue iteration: ${(e as Error).message}`)
+        this.#terminal.writeErrorLine(`Failed to queue iteration: ${(e as Error).message}`)
       );
   }
 
@@ -313,14 +314,14 @@ export class ProjectWatcher {
    * Sets up a raw-mode stdin listener so the user can interact with the watch session
    * via single-key keybinds. Captures the previous raw-mode state for restoration on dispose.
    */
-  private _ensureStdin(): void {
-    if (this._stdinListening || !process.stdin.isTTY) {
+  #ensureStdin(): void {
+    if (this.#stdinListening || !process.stdin.isTTY) {
       return;
     }
     const stdin: NodeJS.ReadStream = process.stdin as NodeJS.ReadStream;
     // Node's ReadStream has an undocumented isRaw property when setRawMode has been used.
     // Capture it in a type-safe way.
-    this._stdinHadRawMode =
+    this.#stdinHadRawMode =
       typeof (stdin as unknown as { isRaw?: boolean }).isRaw === 'boolean'
         ? (stdin as unknown as { isRaw?: boolean }).isRaw
         : undefined; // capture existing raw state
@@ -331,39 +332,39 @@ export class ProjectWatcher {
     }
     stdin.resume();
     stdin.setEncoding('utf8');
-    const handler = (chunk: Buffer | string): void => this._onStdinData(chunk.toString());
+    const handler = (chunk: Buffer | string): void => this.#onStdinData(chunk.toString());
     stdin.on('data', handler);
-    this._onStdinDataBound = handler;
-    this._stdinListening = true;
+    this.#onStdinDataBound = handler;
+    this.#stdinListening = true;
   }
 
   /**
    * Removes the stdin listener and restores the previous raw-mode state.
    */
-  private _disposeStdin(): void {
-    if (!this._stdinListening) {
+  #disposeStdin(): void {
+    if (!this.#stdinListening) {
       return;
     }
     const stdin: NodeJS.ReadStream = process.stdin as NodeJS.ReadStream;
-    if (this._onStdinDataBound) {
-      stdin.off('data', this._onStdinDataBound);
-      this._onStdinDataBound = undefined;
+    if (this.#onStdinDataBound) {
+      stdin.off('data', this.#onStdinDataBound);
+      this.#onStdinDataBound = undefined;
     }
     try {
-      stdin.setRawMode?.(!!this._stdinHadRawMode);
+      stdin.setRawMode?.(!!this.#stdinHadRawMode);
     } catch {
       // ignore
     }
     stdin.unref();
-    this._stdinListening = false;
+    this.#stdinListening = false;
   }
 
   /**
    * Processes a chunk of stdin data, dispatching each character to the appropriate
    * keybind action on the operation graph.
    */
-  private _onStdinData(chunk: string): void {
-    const graph: IOperationGraph = this._graph;
+  #onStdinData(chunk: string): void {
+    const graph: IOperationGraph = this.#graph;
     if (!chunk) return;
     for (const ch of chunk) {
       // Once aborted, only respond to Ctrl+C (force exit)
@@ -376,49 +377,49 @@ export class ProjectWatcher {
       switch (ch) {
         case '\u0003':
         case KEY_QUIT: {
-          this._terminal.writeLine('Aborting watch session... (Ctrl+C to force exit)');
+          this.#terminal.writeLine('Aborting watch session... (Ctrl+C to force exit)');
           graph.abortController.abort();
           break;
         }
         case KEY_ABORT: {
           void graph.abortCurrentIterationAsync().then(() => {
-            this._setStatus('Current iteration aborted');
+            this.#setStatus('Current iteration aborted');
           });
           break;
         }
         case KEY_INVALIDATE: {
           graph.invalidateOperations(undefined, 'manual-invalidation');
-          this._setStatus('All operations invalidated');
+          this.#setStatus('All operations invalidated');
           break;
         }
         case KEY_CLOSE_RUNNERS: {
           void graph.closeRunnersAsync().then(() => {
-            this._setStatus('Closed all runners');
+            this.#setStatus('Closed all runners');
           });
           break;
         }
         case KEY_DEBUG: {
           graph.debugMode = !graph.debugMode;
-          this._setStatus(`Debug mode ${graph.debugMode ? 'enabled' : 'disabled'}`);
+          this.#setStatus(`Debug mode ${graph.debugMode ? 'enabled' : 'disabled'}`);
           break;
         }
         case KEY_VERBOSE: {
           graph.quietMode = !graph.quietMode;
-          this._setStatus(`Verbose mode ${!graph.quietMode ? 'enabled' : 'disabled'}`);
+          this.#setStatus(`Verbose mode ${!graph.quietMode ? 'enabled' : 'disabled'}`);
           break;
         }
         case KEY_PAUSE_RESUME: {
           graph.pauseNextIteration = !graph.pauseNextIteration;
-          this._setStatus(graph.pauseNextIteration ? 'Watch paused' : 'Watch resumed');
+          this.#setStatus(graph.pauseNextIteration ? 'Watch paused' : 'Watch resumed');
           break;
         }
         case KEY_PARALLELISM_UP:
         case '=': {
-          this._adjustParallelism(1);
+          this.#adjustParallelism(1);
           break;
         }
         case KEY_PARALLELISM_DOWN: {
-          this._adjustParallelism(-1);
+          this.#adjustParallelism(-1);
           break;
         }
         case KEY_BUILD: {
@@ -427,9 +428,9 @@ export class ProjectWatcher {
               if (graph.pauseNextIteration === true) {
                 void graph.executeScheduledIterationAsync();
               }
-              this._setStatus('Build iteration queued');
+              this.#setStatus('Build iteration queued');
             } else {
-              this._setStatus('No work to queue');
+              this.#setStatus('No work to queue');
             }
           });
           break;
@@ -446,12 +447,12 @@ export class ProjectWatcher {
    * Adjusts the parallelism on the operation graph by the given delta
    * and reports the result.
    */
-  private _adjustParallelism(delta: number): void {
-    const graph: IOperationGraph = this._graph;
+  #adjustParallelism(delta: number): void {
+    const graph: IOperationGraph = this.#graph;
     const previous: number = graph.parallelism;
     graph.parallelism = previous + delta; // setter will clamp/normalize
     const effective: number = graph.parallelism;
-    this._setStatus(`Parallelism ${effective !== previous ? 'set to' : 'remains'} ${effective}`);
+    this.#setStatus(`Parallelism ${effective !== previous ? 'set to' : 'remains'} ${effective}`);
   }
 }
 
diff --git a/libraries/rush-lib/src/logic/PublishGit.ts b/libraries/rush-lib/src/logic/PublishGit.ts
index f61e504ba22..c7bbdc6823b 100644
--- a/libraries/rush-lib/src/logic/PublishGit.ts
+++ b/libraries/rush-lib/src/logic/PublishGit.ts
@@ -9,14 +9,14 @@ import type { Git } from './Git';
 const DUMMY_BRANCH_NAME: string = '-branch-name-';
 
 export class PublishGit {
-  private readonly _targetBranch: string | undefined;
-  private readonly _gitPath: string;
-  private readonly _gitTagSeparator: string;
+  readonly #targetBranch: string | undefined;
+  readonly #gitPath: string;
+  readonly #gitTagSeparator: string;
 
   public constructor(git: Git, targetBranch: string | undefined) {
-    this._targetBranch = targetBranch;
-    this._gitPath = git.getGitPathOrThrow();
-    this._gitTagSeparator = git.getTagSeparator();
+    this.#targetBranch = targetBranch;
+    this.#gitPath = git.getGitPathOrThrow();
+    this.#gitTagSeparator = git.getTagSeparator();
   }
 
   public async checkoutAsync(branchName: string | undefined, createBranch: boolean = false): Promise<void> {
@@ -28,16 +28,16 @@ export class PublishGit {
     args.push(branchName || DUMMY_BRANCH_NAME);
 
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch,
+      command: this.#gitPath,
       args
     });
   }
 
   public async mergeAsync(branchName: string, verify: boolean = false): Promise<void> {
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch,
+      command: this.#gitPath,
       args: ['merge', branchName, '--no-edit', ...(verify ? [] : ['--no-verify'])]
     });
   }
@@ -52,14 +52,14 @@ export class PublishGit {
     }
 
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch,
+      command: this.#gitPath,
       args: ['branch', '-d', branchName]
     });
     if (hasRemote) {
       await PublishUtilities.execCommandAsync({
-        shouldExecute: !!this._targetBranch,
-        command: this._gitPath,
+        shouldExecute: !!this.#targetBranch,
+        command: this.#gitPath,
         args: ['push', 'origin', '--delete', branchName, ...(verify ? [] : ['--no-verify'])]
       });
     }
@@ -67,24 +67,24 @@ export class PublishGit {
 
   public async pullAsync(verify: boolean = false): Promise<void> {
     const args: string[] = ['pull', 'origin'];
-    if (this._targetBranch) {
-      args.push(this._targetBranch);
+    if (this.#targetBranch) {
+      args.push(this.#targetBranch);
     }
     if (!verify) {
       args.push('--no-verify');
     }
 
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch,
+      command: this.#gitPath,
       args
     });
   }
 
   public async fetchAsync(): Promise<void> {
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch,
+      command: this.#gitPath,
       args: ['fetch', 'origin']
     });
   }
@@ -92,8 +92,8 @@ export class PublishGit {
   public async addChangesAsync(pathspec?: string, workingDirectory?: string): Promise<void> {
     const files: string = pathspec || '.';
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch,
+      command: this.#gitPath,
       args: ['add', files],
       workingDirectory
     });
@@ -110,11 +110,11 @@ export class PublishGit {
     const tagName: string = PublishUtilities.createTagname(
       packageName,
       packageVersion,
-      this._gitTagSeparator
+      this.#gitTagSeparator
     );
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch && shouldExecute,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch && shouldExecute,
+      command: this.#gitPath,
       args: [
         'tag',
         '-a',
@@ -132,11 +132,11 @@ export class PublishGit {
     const tagName: string = PublishUtilities.createTagname(
       packageConfig.packageName,
       packageConfig.packageJson.version,
-      this._gitTagSeparator
+      this.#gitTagSeparator
     );
     const tagOutput: string = (
       await Utilities.executeCommandAndCaptureOutputAsync({
-        command: this._gitPath,
+        command: this.#gitPath,
         args: ['tag', '-l', tagName],
         workingDirectory: packageConfig.projectFolder,
         environment: PublishUtilities.getEnvArgs(),
@@ -149,8 +149,8 @@ export class PublishGit {
 
   public async commitAsync(commitMessage: string, verify: boolean = false): Promise<void> {
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch,
+      command: this.#gitPath,
       args: ['commit', '-m', commitMessage, ...(verify ? [] : ['--no-verify'])]
     });
   }
@@ -161,8 +161,8 @@ export class PublishGit {
     followTags: boolean = true
   ): Promise<void> {
     await PublishUtilities.execCommandAsync({
-      shouldExecute: !!this._targetBranch,
-      command: this._gitPath,
+      shouldExecute: !!this.#targetBranch,
+      command: this.#gitPath,
       // We append "--no-verify" to prevent Git hooks from running.  For example, people may
       // want to invoke "rush change -v" as a pre-push hook.
       args: [
diff --git a/libraries/rush-lib/src/logic/PurgeManager.ts b/libraries/rush-lib/src/logic/PurgeManager.ts
index 58df2009851..3d1225e2202 100644
--- a/libraries/rush-lib/src/logic/PurgeManager.ts
+++ b/libraries/rush-lib/src/logic/PurgeManager.ts
@@ -14,27 +14,27 @@ import type { RushGlobalFolder } from '../api/RushGlobalFolder';
  * This class implements the logic for "rush purge"
  */
 export class PurgeManager {
-  private _rushConfiguration: RushConfiguration;
-  private _rushGlobalFolder: RushGlobalFolder;
-  private _rushUserFolderRecycler: AsyncRecycler;
+  #rushConfiguration: RushConfiguration;
+  #rushGlobalFolder: RushGlobalFolder;
+  #rushUserFolderRecycler: AsyncRecycler;
 
   public readonly commonTempFolderRecycler: AsyncRecycler;
 
   public constructor(rushConfiguration: RushConfiguration, rushGlobalFolder: RushGlobalFolder) {
-    this._rushConfiguration = rushConfiguration;
-    this._rushGlobalFolder = rushGlobalFolder;
+    this.#rushConfiguration = rushConfiguration;
+    this.#rushGlobalFolder = rushGlobalFolder;
 
     const commonAsyncRecyclerPath: string = path.join(
-      this._rushConfiguration.commonTempFolder,
+      this.#rushConfiguration.commonTempFolder,
       RushConstants.rushRecyclerFolderName
     );
     this.commonTempFolderRecycler = new AsyncRecycler(commonAsyncRecyclerPath);
 
     const rushUserAsyncRecyclerPath: string = path.join(
-      this._rushGlobalFolder.path,
+      this.#rushGlobalFolder.path,
       RushConstants.rushRecyclerFolderName
     );
-    this._rushUserFolderRecycler = new AsyncRecycler(rushUserAsyncRecyclerPath);
+    this.#rushUserFolderRecycler = new AsyncRecycler(rushUserAsyncRecyclerPath);
   }
 
   /**
@@ -44,7 +44,7 @@ export class PurgeManager {
   public async startDeleteAllAsync(): Promise<void> {
     await Promise.all([
       this.commonTempFolderRecycler.startDeleteAllAsync(),
-      this._rushUserFolderRecycler.startDeleteAllAsync()
+      this.#rushUserFolderRecycler.startDeleteAllAsync()
     ]);
   }
 
@@ -54,11 +54,11 @@ export class PurgeManager {
   public purgeNormal(): void {
     // Delete everything under common\temp except for the recycler folder itself
     // eslint-disable-next-line no-console
-    console.log('Purging ' + this._rushConfiguration.commonTempFolder);
+    console.log('Purging ' + this.#rushConfiguration.commonTempFolder);
 
     this.commonTempFolderRecycler.moveAllItemsInFolder(
-      this._rushConfiguration.commonTempFolder,
-      this._getMembersToExclude(this._rushConfiguration.commonTempFolder, true)
+      this.#rushConfiguration.commonTempFolder,
+      this.#getMembersToExclude(this.#rushConfiguration.commonTempFolder, true)
     );
   }
 
@@ -71,35 +71,35 @@ export class PurgeManager {
 
     // We will delete everything under ~/.rush/ except for the recycler folder itself
     // eslint-disable-next-line no-console
-    console.log('Purging ' + this._rushGlobalFolder.path);
+    console.log('Purging ' + this.#rushGlobalFolder.path);
 
     // If Rush itself is running under a folder such as  ~/.rush/node-v4.5.6/rush-1.2.3,
     // we cannot delete that folder.
 
     // First purge the node-specific folder, e.g. ~/.rush/node-v4.5.6/* except for rush-1.2.3:
-    this._rushUserFolderRecycler.moveAllItemsInFolder(
-      this._rushGlobalFolder.nodeSpecificPath,
-      this._getMembersToExclude(this._rushGlobalFolder.nodeSpecificPath, true)
+    this.#rushUserFolderRecycler.moveAllItemsInFolder(
+      this.#rushGlobalFolder.nodeSpecificPath,
+      this.#getMembersToExclude(this.#rushGlobalFolder.nodeSpecificPath, true)
     );
 
     // Then purge the the global folder, e.g. ~/.rush/* except for node-v4.5.6
-    this._rushUserFolderRecycler.moveAllItemsInFolder(
-      this._rushGlobalFolder.path,
-      this._getMembersToExclude(this._rushGlobalFolder.path, false)
+    this.#rushUserFolderRecycler.moveAllItemsInFolder(
+      this.#rushGlobalFolder.path,
+      this.#getMembersToExclude(this.#rushGlobalFolder.path, false)
     );
 
     if (
-      this._rushConfiguration.isPnpm &&
-      this._rushConfiguration.pnpmOptions.pnpmStore === 'global' &&
-      this._rushConfiguration.pnpmOptions.pnpmStorePath
+      this.#rushConfiguration.isPnpm &&
+      this.#rushConfiguration.pnpmOptions.pnpmStore === 'global' &&
+      this.#rushConfiguration.pnpmOptions.pnpmStorePath
     ) {
       // eslint-disable-next-line no-console
       console.warn(Colorize.yellow(`Purging the global pnpm-store`));
-      this._rushUserFolderRecycler.moveAllItemsInFolder(this._rushConfiguration.pnpmOptions.pnpmStorePath);
+      this.#rushUserFolderRecycler.moveAllItemsInFolder(this.#rushConfiguration.pnpmOptions.pnpmStorePath);
     }
   }
 
-  private _getMembersToExclude(folderToRecycle: string, showWarning: boolean): string[] {
+  #getMembersToExclude(folderToRecycle: string, showWarning: boolean): string[] {
     // Don't recycle the recycler
     const membersToExclude: string[] = [RushConstants.rushRecyclerFolderName];
 
diff --git a/libraries/rush-lib/src/logic/RepoStateFile.ts b/libraries/rush-lib/src/logic/RepoStateFile.ts
index 499903848fa..990d8e63787 100644
--- a/libraries/rush-lib/src/logic/RepoStateFile.ts
+++ b/libraries/rush-lib/src/logic/RepoStateFile.ts
@@ -47,12 +47,12 @@ const _jsonSchema: JsonSchema = JsonSchema.fromLoadedObject(schemaJson);
  * @public
  */
 export class RepoStateFile {
-  private _pnpmShrinkwrapHash: string | undefined;
-  private _preferredVersionsHash: string | undefined;
-  private _packageJsonInjectedDependenciesHash: string | undefined;
-  private _pnpmCatalogsHash: string | undefined;
-  private _isValid: boolean;
-  private _modified: boolean = false;
+  #pnpmShrinkwrapHash: string | undefined;
+  #preferredVersionsHash: string | undefined;
+  #packageJsonInjectedDependenciesHash: string | undefined;
+  #pnpmCatalogsHash: string | undefined;
+  #isValid: boolean;
+  #modified: boolean = false;
 
   /**
    * Get the absolute file path of the repo-state.json file.
@@ -61,13 +61,13 @@ export class RepoStateFile {
 
   private constructor(repoStateJson: IRepoStateJson | undefined, isValid: boolean, filePath: string) {
     this.filePath = filePath;
-    this._isValid = isValid;
+    this.#isValid = isValid;
 
     if (repoStateJson) {
-      this._pnpmShrinkwrapHash = repoStateJson.pnpmShrinkwrapHash;
-      this._preferredVersionsHash = repoStateJson.preferredVersionsHash;
-      this._packageJsonInjectedDependenciesHash = repoStateJson.packageJsonInjectedDependenciesHash;
-      this._pnpmCatalogsHash = repoStateJson.pnpmCatalogsHash;
+      this.#pnpmShrinkwrapHash = repoStateJson.pnpmShrinkwrapHash;
+      this.#preferredVersionsHash = repoStateJson.preferredVersionsHash;
+      this.#packageJsonInjectedDependenciesHash = repoStateJson.packageJsonInjectedDependenciesHash;
+      this.#pnpmCatalogsHash = repoStateJson.pnpmCatalogsHash;
     }
   }
 
@@ -75,35 +75,35 @@ export class RepoStateFile {
    * The hash of the pnpm shrinkwrap file at the end of the last update.
    */
   public get pnpmShrinkwrapHash(): string | undefined {
-    return this._pnpmShrinkwrapHash;
+    return this.#pnpmShrinkwrapHash;
   }
 
   /**
    * The hash of all preferred versions at the end of the last update.
    */
   public get preferredVersionsHash(): string | undefined {
-    return this._preferredVersionsHash;
+    return this.#preferredVersionsHash;
   }
 
   /**
    * The hash of all preferred versions at the end of the last update.
    */
   public get packageJsonInjectedDependenciesHash(): string | undefined {
-    return this._packageJsonInjectedDependenciesHash;
+    return this.#packageJsonInjectedDependenciesHash;
   }
 
   /**
    * The hash of the PNPM catalog definitions at the end of the last update.
    */
   public get pnpmCatalogsHash(): string | undefined {
-    return this._pnpmCatalogsHash;
+    return this.#pnpmCatalogsHash;
   }
 
   /**
    * If false, the repo-state.json file is not valid and its values cannot be relied upon
    */
   public get isValid(): boolean {
-    return this._isValid;
+    return this.#isValid;
   }
 
   /**
@@ -190,14 +190,14 @@ export class RepoStateFile {
           rushConfiguration.experimentsConfiguration.configuration
         );
 
-        if (this._pnpmShrinkwrapHash !== shrinkwrapFileHash) {
-          this._pnpmShrinkwrapHash = shrinkwrapFileHash;
-          this._modified = true;
+        if (this.#pnpmShrinkwrapHash !== shrinkwrapFileHash) {
+          this.#pnpmShrinkwrapHash = shrinkwrapFileHash;
+          this.#modified = true;
         }
       }
-    } else if (this._pnpmShrinkwrapHash !== undefined) {
-      this._pnpmShrinkwrapHash = undefined;
-      this._modified = true;
+    } else if (this.#pnpmShrinkwrapHash !== undefined) {
+      this.#pnpmShrinkwrapHash = undefined;
+      this.#modified = true;
     }
 
     // Currently, only support saving the preferred versions hash if using workspaces
@@ -206,13 +206,13 @@ export class RepoStateFile {
     if (useWorkspaces) {
       const commonVersions: CommonVersionsConfiguration = subspace.getCommonVersions(variant);
       const preferredVersionsHash: string = commonVersions.getPreferredVersionsHash();
-      if (this._preferredVersionsHash !== preferredVersionsHash) {
-        this._preferredVersionsHash = preferredVersionsHash;
-        this._modified = true;
+      if (this.#preferredVersionsHash !== preferredVersionsHash) {
+        this.#preferredVersionsHash = preferredVersionsHash;
+        this.#modified = true;
       }
-    } else if (this._preferredVersionsHash !== undefined) {
-      this._preferredVersionsHash = undefined;
-      this._modified = true;
+    } else if (this.#preferredVersionsHash !== undefined) {
+      this.#preferredVersionsHash = undefined;
+      this.#modified = true;
     }
 
     if (rushConfiguration.isPnpm) {
@@ -223,65 +223,65 @@ export class RepoStateFile {
       // so we don't need to track the hash value for that subspace
       if (
         packageJsonInjectedDependenciesHash &&
-        packageJsonInjectedDependenciesHash !== this._packageJsonInjectedDependenciesHash
+        packageJsonInjectedDependenciesHash !== this.#packageJsonInjectedDependenciesHash
       ) {
-        this._packageJsonInjectedDependenciesHash = packageJsonInjectedDependenciesHash;
-        this._modified = true;
-      } else if (!packageJsonInjectedDependenciesHash && this._packageJsonInjectedDependenciesHash) {
+        this.#packageJsonInjectedDependenciesHash = packageJsonInjectedDependenciesHash;
+        this.#modified = true;
+      } else if (!packageJsonInjectedDependenciesHash && this.#packageJsonInjectedDependenciesHash) {
         // if packageJsonInjectedDependenciesHash is undefined, but this._packageJsonInjectedDependenciesHash is not
         // means users may turn off the injected installation
         // so we will need to remove unused fields in repo-state.json as well
-        this._packageJsonInjectedDependenciesHash = undefined;
-        this._modified = true;
+        this.#packageJsonInjectedDependenciesHash = undefined;
+        this.#modified = true;
       }
 
       // Track catalog hash to detect when catalog definitions change
       const pnpmCatalogsHash: string | undefined = subspace.getPnpmCatalogsHash();
-      if (pnpmCatalogsHash && pnpmCatalogsHash !== this._pnpmCatalogsHash) {
-        this._pnpmCatalogsHash = pnpmCatalogsHash;
-        this._modified = true;
-      } else if (!pnpmCatalogsHash && this._pnpmCatalogsHash) {
-        this._pnpmCatalogsHash = undefined;
-        this._modified = true;
+      if (pnpmCatalogsHash && pnpmCatalogsHash !== this.#pnpmCatalogsHash) {
+        this.#pnpmCatalogsHash = pnpmCatalogsHash;
+        this.#modified = true;
+      } else if (!pnpmCatalogsHash && this.#pnpmCatalogsHash) {
+        this.#pnpmCatalogsHash = undefined;
+        this.#modified = true;
       }
     }
 
     // Now that the file has been refreshed, we know its contents are valid
-    this._isValid = true;
+    this.#isValid = true;
 
-    return this._saveIfModified();
+    return this.#saveIfModified();
   }
 
   /**
    * Writes the "repo-state.json" file to disk, using the filename that was passed to loadFromFile().
    */
-  private _saveIfModified(): boolean {
-    if (this._modified) {
+  #saveIfModified(): boolean {
+    if (this.#modified) {
       const content: string =
         '// DO NOT MODIFY THIS FILE MANUALLY BUT DO COMMIT IT. It is generated and used by Rush.' +
-        `${NewlineKind.Lf}${this._serialize()}`;
+        `${NewlineKind.Lf}${this.#serialize()}`;
       FileSystem.writeFile(this.filePath, content);
-      this._modified = false;
+      this.#modified = false;
       return true;
     }
 
     return false;
   }
 
-  private _serialize(): string {
+  #serialize(): string {
     // We need to set these one-by-one, since JsonFile.stringify does not like undefined values
     const repoStateJson: IRepoStateJson = {};
-    if (this._pnpmShrinkwrapHash) {
-      repoStateJson.pnpmShrinkwrapHash = this._pnpmShrinkwrapHash;
+    if (this.#pnpmShrinkwrapHash) {
+      repoStateJson.pnpmShrinkwrapHash = this.#pnpmShrinkwrapHash;
     }
-    if (this._preferredVersionsHash) {
-      repoStateJson.preferredVersionsHash = this._preferredVersionsHash;
+    if (this.#preferredVersionsHash) {
+      repoStateJson.preferredVersionsHash = this.#preferredVersionsHash;
     }
-    if (this._packageJsonInjectedDependenciesHash) {
-      repoStateJson.packageJsonInjectedDependenciesHash = this._packageJsonInjectedDependenciesHash;
+    if (this.#packageJsonInjectedDependenciesHash) {
+      repoStateJson.packageJsonInjectedDependenciesHash = this.#packageJsonInjectedDependenciesHash;
     }
-    if (this._pnpmCatalogsHash) {
-      repoStateJson.pnpmCatalogsHash = this._pnpmCatalogsHash;
+    if (this.#pnpmCatalogsHash) {
+      repoStateJson.pnpmCatalogsHash = this.#pnpmCatalogsHash;
     }
 
     return JsonFile.stringify(repoStateJson, { newlineConversion: NewlineKind.Lf });
diff --git a/libraries/rush-lib/src/logic/Telemetry.ts b/libraries/rush-lib/src/logic/Telemetry.ts
index 8d855cd46a0..1915f266ffa 100644
--- a/libraries/rush-lib/src/logic/Telemetry.ts
+++ b/libraries/rush-lib/src/logic/Telemetry.ts
@@ -144,33 +144,33 @@ const MAX_FILE_COUNT: number = 100;
 const ONE_MEGABYTE_IN_BYTES: 1048576 = 1048576;
 
 export class Telemetry {
-  private _enabled: boolean;
-  private _store: ITelemetryData[];
-  private _dataFolder: string;
-  private _rushConfiguration: RushConfiguration;
-  private _rushSession: RushSession;
-  private _flushAsyncTasks: Set<Promise<void>> = new Set();
-  private _telemetryStartTime: number = 0;
+  #enabled: boolean;
+  #store: ITelemetryData[];
+  #dataFolder: string;
+  #rushConfiguration: RushConfiguration;
+  #rushSession: RushSession;
+  private readonly _flushAsyncTasks: Set<Promise<void>> = new Set();
+  #telemetryStartTime: number = 0;
 
   public constructor(rushConfiguration: RushConfiguration, rushSession: RushSession) {
-    this._rushConfiguration = rushConfiguration;
-    this._rushSession = rushSession;
-    this._enabled = this._rushConfiguration.telemetryEnabled;
-    this._store = [];
+    this.#rushConfiguration = rushConfiguration;
+    this.#rushSession = rushSession;
+    this.#enabled = this.#rushConfiguration.telemetryEnabled;
+    this.#store = [];
 
     const folderName: string = 'telemetry';
-    this._dataFolder = path.join(this._rushConfiguration.commonTempFolder, folderName);
+    this.#dataFolder = path.join(this.#rushConfiguration.commonTempFolder, folderName);
   }
 
   public log(telemetryData: ITelemetryData): void {
-    if (!this._enabled) {
+    if (!this.#enabled) {
       return;
     }
     const cpus: os.CpuInfo[] = os.cpus();
     const data: ITelemetryData = {
       ...telemetryData,
       performanceEntries:
-        telemetryData.performanceEntries || collectPerformanceEntries(this._telemetryStartTime),
+        telemetryData.performanceEntries || collectPerformanceEntries(this.#telemetryStartTime),
       machineInfo: telemetryData.machineInfo || {
         machineArchitecture: os.arch(),
         // The Node.js model is sometimes padded, for example:
@@ -184,23 +184,23 @@ export class Telemetry {
       platform: telemetryData.platform || process.platform,
       rushVersion: telemetryData.rushVersion || Rush.version
     };
-    this._telemetryStartTime = performance.now();
-    this._store.push(data);
+    this.#telemetryStartTime = performance.now();
+    this.#store.push(data);
   }
 
   public flush(): void {
-    if (!this._enabled || this._store.length === 0) {
+    if (!this.#enabled || this.#store.length === 0) {
       return;
     }
 
-    const fullPath: string = this._getFilePath();
-    JsonFile.save(this._store, fullPath, { ensureFolderExists: true, ignoreUndefinedValues: true });
-    if (this._rushSession.hooks.flushTelemetry.isUsed()) {
+    const fullPath: string = this.#getFilePath();
+    JsonFile.save(this.#store, fullPath, { ensureFolderExists: true, ignoreUndefinedValues: true });
+    if (this.#rushSession.hooks.flushTelemetry.isUsed()) {
       /**
        * User defined flushTelemetry should not block anything, so we don't await here,
        * and store the promise into a list so that we can await it later.
        */
-      const asyncTaskPromise: Promise<void> = this._rushSession.hooks.flushTelemetry.promise(this._store);
+      const asyncTaskPromise: Promise<void> = this.#rushSession.hooks.flushTelemetry.promise(this.#store);
       this._flushAsyncTasks.add(asyncTaskPromise);
       asyncTaskPromise.then(
         () => {
@@ -212,8 +212,8 @@ export class Telemetry {
       );
     }
 
-    this._store = [];
-    this._cleanUp();
+    this.#store = [];
+    this.#cleanUp();
   }
 
   /**
@@ -224,19 +224,19 @@ export class Telemetry {
   }
 
   public get store(): ITelemetryData[] {
-    return this._store;
+    return this.#store;
   }
 
   /**
    * When there are too many log files, delete the old ones.
    */
-  private _cleanUp(): void {
-    if (FileSystem.exists(this._dataFolder)) {
-      const files: string[] = FileSystem.readFolderItemNames(this._dataFolder);
+  #cleanUp(): void {
+    if (FileSystem.exists(this.#dataFolder)) {
+      const files: string[] = FileSystem.readFolderItemNames(this.#dataFolder);
       if (files.length > MAX_FILE_COUNT) {
         const sortedFiles: string[] = files
           .map((fileName) => {
-            const filePath: string = path.join(this._dataFolder, fileName);
+            const filePath: string = path.join(this.#dataFolder, fileName);
             const stats: FileSystemStats = FileSystem.getStatistics(filePath);
             return {
               filePath: filePath,
@@ -262,9 +262,9 @@ export class Telemetry {
     }
   }
 
-  private _getFilePath(): string {
+  #getFilePath(): string {
     let fileName: string = `telemetry_${new Date().toISOString()}`;
     fileName = fileName.replace(/[\-\:\.]/g, '_') + '.json';
-    return path.join(this._dataFolder, fileName);
+    return path.join(this.#dataFolder, fileName);
   }
 }
diff --git a/libraries/rush-lib/src/logic/TempProjectHelper.ts b/libraries/rush-lib/src/logic/TempProjectHelper.ts
index 10c27d2e847..129b4b2a454 100644
--- a/libraries/rush-lib/src/logic/TempProjectHelper.ts
+++ b/libraries/rush-lib/src/logic/TempProjectHelper.ts
@@ -17,19 +17,19 @@ import type { Subspace } from '../api/Subspace';
 /* eslint-disable no-bitwise */
 
 export class TempProjectHelper {
-  private _rushConfiguration: RushConfiguration;
-  private _subspace: Subspace;
+  #rushConfiguration: RushConfiguration;
+  #subspace: Subspace;
 
   public constructor(rushConfiguration: RushConfiguration, subspace: Subspace) {
-    this._rushConfiguration = rushConfiguration;
-    this._subspace = subspace;
+    this.#rushConfiguration = rushConfiguration;
+    this.#subspace = subspace;
   }
 
   /**
    * Deletes the existing tarball and creates a tarball for the given rush project
    */
   public createTempProjectTarball(rushProject: RushConfigurationProject): void {
-    FileSystem.ensureFolder(path.resolve(this._subspace.getSubspaceTempFolderPath(), 'projects'));
+    FileSystem.ensureFolder(path.resolve(this.#subspace.getSubspaceTempFolderPath(), 'projects'));
     const tarballFile: string = this.getTarballFilePath(rushProject);
     const tempProjectFolder: string = this.getTempProjectFolder(rushProject);
 
@@ -49,7 +49,7 @@ export class TempProjectHelper {
       prefix: npmPackageFolder,
       filter: (tarPath: string, stat: Stats): boolean => {
         if (
-          !this._rushConfiguration.experimentsConfiguration.configuration.noChmodFieldInTarHeaderNormalization
+          !this.#rushConfiguration.experimentsConfiguration.configuration.noChmodFieldInTarHeaderNormalization
         ) {
           stat.mode =
             (stat.mode & ~0x1ff) | PosixModeBits.AllRead | PosixModeBits.UserWrite | PosixModeBits.AllExecute;
@@ -67,7 +67,7 @@ export class TempProjectHelper {
    */
   public getTarballFilePath(project: RushConfigurationProject): string {
     return path.join(
-      this._subspace.getSubspaceTempFolderPath(),
+      this.#subspace.getSubspaceTempFolderPath(),
       RushConstants.rushTempProjectsFolderName,
       `${project.unscopedTempProjectName}.tgz`
     );
@@ -76,7 +76,7 @@ export class TempProjectHelper {
   public getTempProjectFolder(rushProject: RushConfigurationProject): string {
     const unscopedTempProjectName: string = rushProject.unscopedTempProjectName;
     return path.join(
-      this._subspace.getSubspaceTempFolderPath(),
+      this.#subspace.getSubspaceTempFolderPath(),
       RushConstants.rushTempProjectsFolderName,
       unscopedTempProjectName
     );
diff --git a/libraries/rush-lib/src/logic/UnlinkManager.ts b/libraries/rush-lib/src/logic/UnlinkManager.ts
index d77a73b97b4..c0fb760b8c8 100644
--- a/libraries/rush-lib/src/logic/UnlinkManager.ts
+++ b/libraries/rush-lib/src/logic/UnlinkManager.ts
@@ -16,10 +16,10 @@ import { RushConstants } from './RushConstants';
  * This class implements the logic for "rush unlink"
  */
 export class UnlinkManager {
-  private _rushConfiguration: RushConfiguration;
+  #rushConfiguration: RushConfiguration;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   /**
@@ -30,7 +30,7 @@ export class UnlinkManager {
    */
   public async unlinkAsync(force: boolean = false): Promise<boolean> {
     const useWorkspaces: boolean =
-      this._rushConfiguration.pnpmOptions && this._rushConfiguration.pnpmOptions.useWorkspaces;
+      this.#rushConfiguration.pnpmOptions && this.#rushConfiguration.pnpmOptions.useWorkspaces;
     if (!force && useWorkspaces) {
       // eslint-disable-next-line no-console
       console.log(
@@ -43,11 +43,11 @@ export class UnlinkManager {
     }
 
     await new FlagFile(
-      this._rushConfiguration.defaultSubspace.getSubspaceTempFolderPath(),
+      this.#rushConfiguration.defaultSubspace.getSubspaceTempFolderPath(),
       RushConstants.lastLinkFlagFilename,
       {}
     ).clearAsync();
-    return this._deleteProjectFiles();
+    return this.#deleteProjectFiles();
   }
 
   /**
@@ -57,10 +57,10 @@ export class UnlinkManager {
    *
    * Returns true if anything was deleted
    * */
-  private _deleteProjectFiles(): boolean {
+  #deleteProjectFiles(): boolean {
     let didDeleteAnything: boolean = false;
 
-    for (const rushProject of this._rushConfiguration.projects) {
+    for (const rushProject of this.#rushConfiguration.projects) {
       const localModuleFolder: string = path.join(rushProject.projectFolder, 'node_modules');
       if (FileSystem.exists(localModuleFolder)) {
         // eslint-disable-next-line no-console
diff --git a/libraries/rush-lib/src/logic/VersionManager.ts b/libraries/rush-lib/src/logic/VersionManager.ts
index ac41623f215..b42f689c021 100644
--- a/libraries/rush-lib/src/logic/VersionManager.ts
+++ b/libraries/rush-lib/src/logic/VersionManager.ts
@@ -20,9 +20,9 @@ import { DependencySpecifier } from './DependencySpecifier';
 import { cloneDeep } from '../utilities/objectUtilities';
 
 export class VersionManager {
-  private _rushConfiguration: RushConfiguration;
-  private _userEmail: string;
-  private _versionPolicyConfiguration: VersionPolicyConfiguration;
+  #rushConfiguration: RushConfiguration;
+  #userEmail: string;
+  #versionPolicyConfiguration: VersionPolicyConfiguration;
 
   public readonly updatedProjects: Map<string, IPackageJson>;
   public readonly changeFiles: Map<string, ChangeFile>;
@@ -32,11 +32,11 @@ export class VersionManager {
     userEmail: string,
     versionPolicyConfiguration: VersionPolicyConfiguration
   ) {
-    this._rushConfiguration = rushConfiguration;
-    this._userEmail = userEmail;
-    this._versionPolicyConfiguration = versionPolicyConfiguration
+    this.#rushConfiguration = rushConfiguration;
+    this.#userEmail = userEmail;
+    this.#versionPolicyConfiguration = versionPolicyConfiguration
       ? versionPolicyConfiguration
-      : this._rushConfiguration.versionPolicyConfiguration;
+      : this.#rushConfiguration.versionPolicyConfiguration;
 
     this.updatedProjects = new Map<string, IPackageJson>();
     this.changeFiles = new Map<string, ChangeFile>();
@@ -52,7 +52,7 @@ export class VersionManager {
    * @param force -- update even when project version is higher than policy version.
    */
   public ensure(versionPolicyName?: string, shouldCommit?: boolean, force?: boolean): void {
-    this._ensure(versionPolicyName, shouldCommit, force);
+    this.#ensure(versionPolicyName, shouldCommit, force);
   }
 
   /**
@@ -73,26 +73,26 @@ export class VersionManager {
     shouldCommit?: boolean
   ): Promise<void> {
     // Bump all the lock step version policies.
-    this._versionPolicyConfiguration.bump(lockStepVersionPolicyName, bumpType, identifier, shouldCommit);
+    this.#versionPolicyConfiguration.bump(lockStepVersionPolicyName, bumpType, identifier, shouldCommit);
 
     // Update packages and generate change files due to lock step bump.
-    this._ensure(lockStepVersionPolicyName, shouldCommit);
+    this.#ensure(lockStepVersionPolicyName, shouldCommit);
 
     // Refresh rush configuration since we may have modified the package.json versions
     // when calling this._ensure(...)
-    this._rushConfiguration = RushConfiguration.loadFromConfigurationFile(
-      this._rushConfiguration.rushJsonFile
+    this.#rushConfiguration = RushConfiguration.loadFromConfigurationFile(
+      this.#rushConfiguration.rushJsonFile
     );
 
     // Update projects based on individual policies
     const changeManager: ChangeManager = new ChangeManager(
-      this._rushConfiguration,
-      this._getManuallyVersionedProjects()
+      this.#rushConfiguration,
+      this.#getManuallyVersionedProjects()
     );
 
     await changeManager.loadAsync();
     if (changeManager.hasChanges()) {
-      changeManager.validateChanges(this._versionPolicyConfiguration);
+      changeManager.validateChanges(this.#versionPolicyConfiguration);
       changeManager.apply(!!shouldCommit)!.forEach((packageJson) => {
         this.updatedProjects.set(packageJson.name, packageJson);
       });
@@ -101,40 +101,40 @@ export class VersionManager {
 
     // Refresh rush configuration again, since we've further modified the package.json files
     // by calling changeManager.apply(...)
-    this._rushConfiguration = RushConfiguration.loadFromConfigurationFile(
-      this._rushConfiguration.rushJsonFile
+    this.#rushConfiguration = RushConfiguration.loadFromConfigurationFile(
+      this.#rushConfiguration.rushJsonFile
     );
   }
 
-  private _ensure(versionPolicyName?: string, shouldCommit?: boolean, force?: boolean): void {
-    this._updateVersionsByPolicy(versionPolicyName, force);
+  #ensure(versionPolicyName?: string, shouldCommit?: boolean, force?: boolean): void {
+    this.#updateVersionsByPolicy(versionPolicyName, force);
 
     let changed: boolean = false;
     do {
       changed = false;
       // Update all dependencies if needed.
-      const dependenciesUpdated: boolean = this._updateDependencies();
+      const dependenciesUpdated: boolean = this.#updateDependencies();
       changed = changed || dependenciesUpdated;
     } while (changed);
 
     if (shouldCommit) {
-      this._updatePackageJsonFiles();
+      this.#updatePackageJsonFiles();
       this.changeFiles.forEach((changeFile) => {
         changeFile.writeSync();
       });
     }
   }
 
-  private _getManuallyVersionedProjects(): Set<string> | undefined {
+  #getManuallyVersionedProjects(): Set<string> | undefined {
     const lockStepVersionPolicyNames: Set<string> = new Set<string>();
 
-    this._versionPolicyConfiguration.versionPolicies.forEach((versionPolicy) => {
+    this.#versionPolicyConfiguration.versionPolicies.forEach((versionPolicy) => {
       if (versionPolicy instanceof LockStepVersionPolicy && versionPolicy.nextBump !== undefined) {
         lockStepVersionPolicyNames.add(versionPolicy.policyName);
       }
     });
     const lockStepProjectNames: Set<string> = new Set<string>();
-    this._rushConfiguration.projects.forEach((rushProject) => {
+    this.#rushConfiguration.projects.forEach((rushProject) => {
       if (lockStepVersionPolicyNames.has(rushProject.versionPolicyName!)) {
         lockStepProjectNames.add(rushProject.packageName);
       }
@@ -142,18 +142,18 @@ export class VersionManager {
     return lockStepProjectNames;
   }
 
-  private _updateVersionsByPolicy(versionPolicyName?: string, force?: boolean): boolean {
+  #updateVersionsByPolicy(versionPolicyName?: string, force?: boolean): boolean {
     let changed: boolean = false;
 
     // Update versions based on version policy
-    this._rushConfiguration.projects.forEach((rushProject) => {
+    this.#rushConfiguration.projects.forEach((rushProject) => {
       const projectVersionPolicyName: string | undefined = rushProject.versionPolicyName;
       if (
         projectVersionPolicyName &&
         (!versionPolicyName || projectVersionPolicyName === versionPolicyName)
       ) {
         const versionPolicy: VersionPolicy =
-          this._versionPolicyConfiguration.getVersionPolicy(projectVersionPolicyName);
+          this.#versionPolicyConfiguration.getVersionPolicy(projectVersionPolicyName);
 
         const oldVersion: string =
           this.updatedProjects.get(rushProject.packageName)?.version || rushProject.packageJson.version;
@@ -163,8 +163,8 @@ export class VersionManager {
         if (updatedProject) {
           this.updatedProjects.set(updatedProject.name, updatedProject);
           // No need to create an entry for prerelease version bump.
-          if (!this._isPrerelease(updatedProject.version) && rushProject.isMainProject) {
-            this._addChangeInfo(updatedProject.name, [this._createChangeInfo(updatedProject, rushProject)]);
+          if (!this.#isPrerelease(updatedProject.version) && rushProject.isMainProject) {
+            this.#addChangeInfo(updatedProject.name, [this.#createChangeInfo(updatedProject, rushProject)]);
           }
         }
       }
@@ -173,11 +173,11 @@ export class VersionManager {
     return changed;
   }
 
-  private _isPrerelease(version: string): boolean {
+  #isPrerelease(version: string): boolean {
     return !!semver.prerelease(version);
   }
 
-  private _addChangeInfo(packageName: string, changeInfos: IChangeInfo[]): void {
+  #addChangeInfo(packageName: string, changeInfos: IChangeInfo[]): void {
     if (!changeInfos.length) {
       return;
     }
@@ -187,9 +187,9 @@ export class VersionManager {
         {
           changes: [],
           packageName: packageName,
-          email: this._userEmail
+          email: this.#userEmail
         },
-        this._rushConfiguration
+        this.#rushConfiguration
       );
       this.changeFiles.set(packageName, changeFile);
     }
@@ -198,10 +198,10 @@ export class VersionManager {
     });
   }
 
-  private _updateDependencies(): boolean {
+  #updateDependencies(): boolean {
     let updated: boolean = false;
 
-    this._rushConfiguration.projects.forEach((rushProject) => {
+    this.#rushConfiguration.projects.forEach((rushProject) => {
       let clonedProject: IPackageJson | undefined = this.updatedProjects.get(rushProject.packageName);
       let projectVersionChanged: boolean = true;
 
@@ -210,7 +210,7 @@ export class VersionManager {
         projectVersionChanged = false;
       }
 
-      const dependenciesUpdated: boolean = this._updateProjectAllDependencies(
+      const dependenciesUpdated: boolean = this.#updateProjectAllDependencies(
         rushProject,
         clonedProject!,
         projectVersionChanged
@@ -222,7 +222,7 @@ export class VersionManager {
     return updated;
   }
 
-  private _updateProjectAllDependencies(
+  #updateProjectAllDependencies(
     rushProject: RushConfigurationProject,
     clonedProject: IPackageJson,
     projectVersionChanged: boolean
@@ -233,7 +233,7 @@ export class VersionManager {
     const changes: IChangeInfo[] = [];
     let updated: boolean = false;
     if (
-      this._updateProjectDependencies(
+      this.#updateProjectDependencies(
         clonedProject.dependencies,
         changes,
         clonedProject,
@@ -244,7 +244,7 @@ export class VersionManager {
       updated = true;
     }
     if (
-      this._updateProjectDependencies(
+      this.#updateProjectDependencies(
         clonedProject.devDependencies,
         changes,
         clonedProject,
@@ -255,7 +255,7 @@ export class VersionManager {
       updated = true;
     }
     if (
-      this._updateProjectDependencies(
+      this.#updateProjectDependencies(
         clonedProject.peerDependencies,
         changes,
         clonedProject,
@@ -268,13 +268,13 @@ export class VersionManager {
 
     if (updated) {
       this.updatedProjects.set(clonedProject.name, clonedProject);
-      this._addChangeInfo(clonedProject.name, changes);
+      this.#addChangeInfo(clonedProject.name, changes);
     }
 
     return updated;
   }
 
-  private _updateProjectDependencies(
+  #updateProjectDependencies(
     dependencies: { [key: string]: string } | undefined,
     changes: IChangeInfo[],
     clonedProject: IPackageJson,
@@ -303,8 +303,8 @@ export class VersionManager {
 
         if (newDependencyVersion !== oldDependencyVersion) {
           updated = true;
-          if (this._shouldTrackDependencyChange(rushProject, updatedDependentProjectName)) {
-            this._trackDependencyChange(
+          if (this.#shouldTrackDependencyChange(rushProject, updatedDependentProjectName)) {
+            this.#trackDependencyChange(
               changes,
               clonedProject,
               projectVersionChanged,
@@ -320,12 +320,12 @@ export class VersionManager {
     return updated;
   }
 
-  private _shouldTrackDependencyChange(
+  #shouldTrackDependencyChange(
     rushProject: RushConfigurationProject,
     dependencyName: string
   ): boolean {
     const dependencyRushProject: RushConfigurationProject | undefined =
-      this._rushConfiguration.projectsByName.get(dependencyName);
+      this.#rushConfiguration.projectsByName.get(dependencyName);
 
     return (
       !!dependencyRushProject &&
@@ -337,7 +337,7 @@ export class VersionManager {
     );
   }
 
-  private _trackDependencyChange(
+  #trackDependencyChange(
     changes: IChangeInfo[],
     clonedProject: IPackageJson,
     projectVersionChanged: boolean,
@@ -353,7 +353,7 @@ export class VersionManager {
       !semver.satisfies(updatedDependentProject.version, oldSpecifier.versionSpecifier) &&
       !projectVersionChanged
     ) {
-      this._addChange(changes, {
+      this.#addChange(changes, {
         changeType: ChangeType.patch,
         packageName: clonedProject.name
       });
@@ -361,8 +361,8 @@ export class VersionManager {
 
     // If current version is not a prerelease version and new dependency is also not a prerelease version,
     // add change entry. Otherwise, too many changes will be created for frequent releases.
-    if (!this._isPrerelease(updatedDependentProject.version) && !this._isPrerelease(clonedProject.version)) {
-      this._addChange(changes, {
+    if (!this.#isPrerelease(updatedDependentProject.version) && !this.#isPrerelease(clonedProject.version)) {
+      this.#addChange(changes, {
         changeType: ChangeType.dependency,
         comment:
           `Dependency ${updatedDependentProject.name} version bump from ${oldDependencyVersion}` +
@@ -372,7 +372,7 @@ export class VersionManager {
     }
   }
 
-  private _addChange(changes: IChangeInfo[], newChange: IChangeInfo): void {
+  #addChange(changes: IChangeInfo[], newChange: IChangeInfo): void {
     const exists: boolean = changes.some((changeInfo) => {
       return (
         changeInfo.author === newChange.author &&
@@ -388,10 +388,10 @@ export class VersionManager {
     }
   }
 
-  private _updatePackageJsonFiles(): void {
+  #updatePackageJsonFiles(): void {
     this.updatedProjects.forEach((newPackageJson, packageName) => {
       const rushProject: RushConfigurationProject | undefined =
-        this._rushConfiguration.getProjectByName(packageName);
+        this.#rushConfiguration.getProjectByName(packageName);
       // Update package.json
       if (rushProject) {
         const packagePath: string = path.join(rushProject.projectFolder, FileConstants.PackageJson);
@@ -400,7 +400,7 @@ export class VersionManager {
     });
   }
 
-  private _createChangeInfo(
+  #createChangeInfo(
     newPackageJson: IPackageJson,
     rushProject: RushConfigurationProject
   ): IChangeInfo {
diff --git a/libraries/rush-lib/src/logic/base/BaseInstallManager.ts b/libraries/rush-lib/src/logic/base/BaseInstallManager.ts
index fa21aed84c0..5322df003b9 100644
--- a/libraries/rush-lib/src/logic/base/BaseInstallManager.ts
+++ b/libraries/rush-lib/src/logic/base/BaseInstallManager.ts
@@ -75,9 +75,9 @@ const gitLfsHooks: ReadonlySet<string> = new Set(['post-checkout', 'post-commit'
  * This class implements common logic between "rush install" and "rush update".
  */
 export abstract class BaseInstallManager {
-  private readonly _commonTempLinkFlag: FlagFile;
-  private _npmSetupValidated: boolean = false;
-  private _syncNpmrcAlreadyCalled: boolean = false;
+  readonly #commonTempLinkFlag: FlagFile;
+  #npmSetupValidated: boolean = false;
+  #syncNpmrcAlreadyCalled: boolean = false;
 
   protected readonly _terminal: ITerminal;
 
@@ -100,7 +100,7 @@ export abstract class BaseInstallManager {
     this.installRecycler = purgeManager.commonTempFolderRecycler;
     this.options = options;
 
-    this._commonTempLinkFlag = new FlagFile(
+    this.#commonTempLinkFlag = new FlagFile(
       options.subspace.getSubspaceTempFolderPath(),
       RushConstants.lastLinkFlagFilename,
       {}
@@ -224,7 +224,7 @@ export abstract class BaseInstallManager {
       if (!this.rushConfiguration.rushConfigurationJson.suppressRushIsPublicVersionCheck) {
         let publishedRelease: boolean | undefined;
         try {
-          publishedRelease = await this._checkIfReleaseIsPublishedAsync();
+          publishedRelease = await this.#checkIfReleaseIsPublishedAsync();
         } catch {
           // If the user is working in an environment that can't reach the registry,
           // don't bother them with errors.
@@ -244,7 +244,7 @@ export abstract class BaseInstallManager {
 
         // Since we're going to be tampering with common/node_modules, delete the "rush link" flag file if it exists;
         // this ensures that a full "rush link" is required next time
-        await this._commonTempLinkFlag.clearAsync();
+        await this.#commonTempLinkFlag.clearAsync();
       }
 
       // Give plugins an opportunity to act before invoking the installation process
@@ -448,7 +448,7 @@ export abstract class BaseInstallManager {
     // than whatever pnpm would emit.
     detectAndReportWorkspaceCycles(this.rushConfiguration, terminal);
 
-    await this._installGitHooksAsync();
+    await this.#installGitHooksAsync();
 
     const approvedPackagesChecker: ApprovedPackagesChecker = new ApprovedPackagesChecker(
       this.rushConfiguration
@@ -561,7 +561,7 @@ export abstract class BaseInstallManager {
       createIfMissing: this.rushConfiguration.subspacesFeatureEnabled,
       supportEnvVarFallbackSyntax: this.rushConfiguration.isPnpm
     });
-    this._syncNpmrcAlreadyCalled = true;
+    this.#syncNpmrcAlreadyCalled = true;
 
     const npmrcHash: string | undefined = npmrcText
       ? crypto.createHash('sha1').update(npmrcText).digest('hex')
@@ -648,7 +648,7 @@ export abstract class BaseInstallManager {
       ]);
     shrinkwrapIsUpToDate = shrinkwrapIsUpToDate && !this.options.recheckShrinkwrap;
 
-    this._syncTempShrinkwrap(subspace, variant, shrinkwrapFile);
+    this.#syncTempShrinkwrap(subspace, variant, shrinkwrapFile);
 
     // Write out the reported warnings
     if (shrinkwrapWarnings.length > 0) {
@@ -698,7 +698,7 @@ export abstract class BaseInstallManager {
   /**
    * Git hooks are only installed if the repo opts in by including files in /common/git-hooks
    */
-  private async _installGitHooksAsync(): Promise<void> {
+  async #installGitHooksAsync(): Promise<void> {
     const hookSource: string = path.join(this.rushConfiguration.commonFolder, 'git-hooks');
     const git: Git = new Git(this.rushConfiguration);
     const hookDestination: string | undefined = git.getHooksFolder();
@@ -1026,7 +1026,7 @@ ${gitLfsHookHandling}
     }
   }
 
-  private async _checkIfReleaseIsPublishedAsync(): Promise<boolean> {
+  async #checkIfReleaseIsPublishedAsync(): Promise<boolean> {
     const lastCheckFile: string = path.join(
       this.rushGlobalFolder.nodeSpecificPath,
       'rush-' + Rush.version,
@@ -1064,7 +1064,7 @@ ${gitLfsHookHandling}
 
     try {
       // For this check we use the official registry, not the private registry
-      const publishedRelease: boolean = await this._queryIfReleaseIsPublishedAsync(
+      const publishedRelease: boolean = await this.#queryIfReleaseIsPublishedAsync(
         'https://registry.npmjs.org:443'
       );
       // Cache the result
@@ -1077,7 +1077,7 @@ ${gitLfsHookHandling}
   }
 
   // Helper for checkIfReleaseIsPublished()
-  private async _queryIfReleaseIsPublishedAsync(registryUrl: string): Promise<boolean> {
+  async #queryIfReleaseIsPublishedAsync(registryUrl: string): Promise<boolean> {
     let queryUrl: string = registryUrl;
     if (queryUrl[-1] !== '/') {
       queryUrl += '/';
@@ -1129,7 +1129,7 @@ ${gitLfsHookHandling}
     return true;
   }
 
-  private _syncTempShrinkwrap(
+  #syncTempShrinkwrap(
     subspace: Subspace,
     variant: string | undefined,
     shrinkwrapFile: BaseShrinkwrapFile | undefined
@@ -1160,7 +1160,7 @@ ${gitLfsHookHandling}
   }
 
   protected async validateNpmSetupAsync(): Promise<void> {
-    if (this._npmSetupValidated) {
+    if (this.#npmSetupValidated) {
       return;
     }
 
@@ -1168,7 +1168,7 @@ ${gitLfsHookHandling}
       const setupPackageRegistry: SetupPackageRegistry = new SetupPackageRegistry({
         rushConfiguration: this.rushConfiguration,
         isDebug: this.options.debug,
-        syncNpmrcAlreadyCalled: this._syncNpmrcAlreadyCalled
+        syncNpmrcAlreadyCalled: this.#syncNpmrcAlreadyCalled
       });
       const valid: boolean = await setupPackageRegistry.checkOnlyAsync();
       if (!valid) {
@@ -1189,6 +1189,6 @@ ${gitLfsHookHandling}
       }
     }
 
-    this._npmSetupValidated = true;
+    this.#npmSetupValidated = true;
   }
 }
diff --git a/libraries/rush-lib/src/logic/base/BasePackage.ts b/libraries/rush-lib/src/logic/base/BasePackage.ts
index 2a1fb304a0d..4491c499742 100644
--- a/libraries/rush-lib/src/logic/base/BasePackage.ts
+++ b/libraries/rush-lib/src/logic/base/BasePackage.ts
@@ -103,7 +103,7 @@ export class BasePackage {
    * The child packages are not necessarily dependencies of this package.
    */
   public children: BasePackage[];
-  private _childrenByName: Map<string, BasePackage>;
+  #childrenByName: Map<string, BasePackage>;
 
   protected constructor(
     name: string,
@@ -128,7 +128,7 @@ export class BasePackage {
     }
 
     this.children = [];
-    this._childrenByName = new Map<string, BasePackage>();
+    this.#childrenByName = new Map<string, BasePackage>();
   }
 
   /**
@@ -186,16 +186,16 @@ export class BasePackage {
     if (child.parent) {
       throw new Error('Child already has a parent');
     }
-    if (this._childrenByName.has(child.installedName)) {
+    if (this.#childrenByName.has(child.installedName)) {
       throw new Error(`Child already exists: ${child.installedName}`);
     }
     child.parent = this;
     this.children.push(child);
-    this._childrenByName.set(child.installedName, child);
+    this.#childrenByName.set(child.installedName, child);
   }
 
   public getChildByName(childPackageName: string): BasePackage | undefined {
-    return this._childrenByName.get(childPackageName);
+    return this.#childrenByName.get(childPackageName);
   }
 
   public printTree(indent?: string): void {
diff --git a/libraries/rush-lib/src/logic/base/BaseShrinkwrapFile.ts b/libraries/rush-lib/src/logic/base/BaseShrinkwrapFile.ts
index 04d64cc8ebd..7a79dbc1ac3 100644
--- a/libraries/rush-lib/src/logic/base/BaseShrinkwrapFile.ts
+++ b/libraries/rush-lib/src/logic/base/BaseShrinkwrapFile.ts
@@ -66,7 +66,7 @@ export abstract class BaseShrinkwrapFile {
       return false;
     }
 
-    return this._checkDependencyVersion(dependencySpecifier, shrinkwrapDependency);
+    return this.#checkDependencyVersion(dependencySpecifier, shrinkwrapDependency);
   }
 
   /**
@@ -100,7 +100,7 @@ export abstract class BaseShrinkwrapFile {
       return false;
     }
 
-    return this._checkDependencyVersion(dependencySpecifier, shrinkwrapDependency);
+    return this.#checkDependencyVersion(dependencySpecifier, shrinkwrapDependency);
   }
 
   /**
@@ -180,7 +180,7 @@ export abstract class BaseShrinkwrapFile {
     return result;
   }
 
-  private _checkDependencyVersion(
+  #checkDependencyVersion(
     projectDependency: DependencySpecifier,
     shrinkwrapDependency: DependencySpecifier
   ): boolean {
diff --git a/libraries/rush-lib/src/logic/buildCache/OperationBuildCache.ts b/libraries/rush-lib/src/logic/buildCache/OperationBuildCache.ts
index b7f98903827..bfcd964a6f0 100644
--- a/libraries/rush-lib/src/logic/buildCache/OperationBuildCache.ts
+++ b/libraries/rush-lib/src/logic/buildCache/OperationBuildCache.ts
@@ -129,15 +129,15 @@ export function _setTarUtilityPromiseForTesting(
  * @internal
  */
 export class OperationBuildCache {
-  private readonly _project: RushConfigurationProject;
-  private readonly _localBuildCacheProvider: FileSystemBuildCacheProvider;
-  private readonly _cloudBuildCacheProvider: ICloudBuildCacheProvider | undefined;
-  private readonly _buildCacheEnabled: boolean;
-  private readonly _cacheWriteEnabled: boolean;
-  private readonly _projectOutputFolderNames: ReadonlyArray<string>;
-  private readonly _cacheId: string | undefined;
-  private readonly _excludeAppleDoubleFiles: boolean;
-  private readonly _useDirectFileTransfersForBuildCache: boolean;
+  readonly #project: RushConfigurationProject;
+  readonly #localBuildCacheProvider: FileSystemBuildCacheProvider;
+  readonly #cloudBuildCacheProvider: ICloudBuildCacheProvider | undefined;
+  readonly #buildCacheEnabled: boolean;
+  readonly #cacheWriteEnabled: boolean;
+  readonly #projectOutputFolderNames: ReadonlyArray<string>;
+  readonly #cacheId: string | undefined;
+  readonly #excludeAppleDoubleFiles: boolean;
+  readonly #useDirectFileTransfersForBuildCache: boolean;
 
   private constructor(cacheId: string | undefined, options: IProjectBuildCacheOptions) {
     const {
@@ -152,19 +152,19 @@ export class OperationBuildCache {
       excludeAppleDoubleFiles,
       useDirectFileTransfersForBuildCache
     } = options;
-    this._project = project;
-    this._localBuildCacheProvider = localCacheProvider;
-    this._cloudBuildCacheProvider = cloudCacheProvider;
-    this._buildCacheEnabled = buildCacheEnabled;
-    this._cacheWriteEnabled = cacheWriteEnabled;
-    this._projectOutputFolderNames = projectOutputFolderNames || [];
-    this._cacheId = cacheId;
-    this._excludeAppleDoubleFiles = excludeAppleDoubleFiles && process.platform === 'darwin';
-    this._useDirectFileTransfersForBuildCache = useDirectFileTransfersForBuildCache;
+    this.#project = project;
+    this.#localBuildCacheProvider = localCacheProvider;
+    this.#cloudBuildCacheProvider = cloudCacheProvider;
+    this.#buildCacheEnabled = buildCacheEnabled;
+    this.#cacheWriteEnabled = cacheWriteEnabled;
+    this.#projectOutputFolderNames = projectOutputFolderNames || [];
+    this.#cacheId = cacheId;
+    this.#excludeAppleDoubleFiles = excludeAppleDoubleFiles && process.platform === 'darwin';
+    this.#useDirectFileTransfersForBuildCache = useDirectFileTransfersForBuildCache;
   }
 
   public get cacheId(): string | undefined {
-    return this._cacheId;
+    return this.#cacheId;
   }
 
   public static getOperationBuildCache(options: IProjectBuildCacheOptions): OperationBuildCache {
@@ -202,33 +202,33 @@ export class OperationBuildCache {
   }
 
   public async tryRestoreFromCacheAsync(terminal: ITerminal, specifiedCacheId?: string): Promise<boolean> {
-    const cacheId: string | undefined = specifiedCacheId || this._cacheId;
+    const cacheId: string | undefined = specifiedCacheId || this.#cacheId;
     if (!cacheId) {
       terminal.writeWarningLine('Unable to get cache ID. Ensure Git is installed.');
       return false;
     }
 
-    if (!this._buildCacheEnabled) {
+    if (!this.#buildCacheEnabled) {
       // Skip reading local and cloud build caches, without any noise
       return false;
     }
 
     let localCacheEntryPath: string | undefined =
-      await this._localBuildCacheProvider.tryGetCacheEntryPathByIdAsync(terminal, cacheId);
+      await this.#localBuildCacheProvider.tryGetCacheEntryPathByIdAsync(terminal, cacheId);
     let cloudCacheHit: boolean = false;
     let updateLocalCacheSuccess: boolean | undefined;
-    if (!localCacheEntryPath && this._cloudBuildCacheProvider) {
+    if (!localCacheEntryPath && this.#cloudBuildCacheProvider) {
       terminal.writeVerboseLine(
         'This project was not found in the local build cache. Querying the cloud build cache.'
       );
 
       if (
-        this._useDirectFileTransfersForBuildCache &&
-        this._cloudBuildCacheProvider.tryDownloadCacheEntryToFileAsync
+        this.#useDirectFileTransfersForBuildCache &&
+        this.#cloudBuildCacheProvider.tryDownloadCacheEntryToFileAsync
       ) {
         // Use file-based path to avoid loading the entire cache entry into memory.
         // The provider downloads directly to a temp file that is atomically moved into place.
-        const targetPath: string = this._localBuildCacheProvider.getCacheEntryPath(cacheId);
+        const targetPath: string = this.#localBuildCacheProvider.getCacheEntryPath(cacheId);
 
         // If multiple local Rush processes race to restore the same cache entry (e.g. parallel
         // "rush build" invocations on the same machine or CI agent), avoid redundant downloads by
@@ -264,7 +264,7 @@ export class OperationBuildCache {
             const tempTargetPath: string = _getTempLocalCacheEntryPath(targetPath);
             try {
               const downloadedToTempFile: boolean =
-                await this._cloudBuildCacheProvider.tryDownloadCacheEntryToFileAsync(
+                await this.#cloudBuildCacheProvider.tryDownloadCacheEntryToFileAsync(
                   terminal,
                   cacheId,
                   tempTargetPath
@@ -305,11 +305,11 @@ export class OperationBuildCache {
         }
       } else {
         const cacheEntryBuffer: Buffer | undefined =
-          await this._cloudBuildCacheProvider.tryGetCacheEntryBufferByIdAsync(terminal, cacheId);
+          await this.#cloudBuildCacheProvider.tryGetCacheEntryBufferByIdAsync(terminal, cacheId);
         if (cacheEntryBuffer) {
           cloudCacheHit = true;
           try {
-            localCacheEntryPath = await this._localBuildCacheProvider.trySetCacheEntryBufferAsync(
+            localCacheEntryPath = await this.#localBuildCacheProvider.trySetCacheEntryBufferAsync(
               terminal,
               cacheId,
               cacheEntryBuffer
@@ -331,12 +331,12 @@ export class OperationBuildCache {
     terminal.writeLine('Build cache hit.');
     terminal.writeVerboseLine(`Cache key: ${cacheId}`);
 
-    const projectFolderPath: string = this._project.projectFolder;
+    const projectFolderPath: string = this.#project.projectFolder;
 
     // Purge output folders
-    terminal.writeVerboseLine(`Clearing cached folders: ${this._projectOutputFolderNames.join(', ')}`);
+    terminal.writeVerboseLine(`Clearing cached folders: ${this.#projectOutputFolderNames.join(', ')}`);
     await Promise.all(
-      this._projectOutputFolderNames.map((outputFolderName: string) =>
+      this.#projectOutputFolderNames.map((outputFolderName: string) =>
         FileSystem.deleteFolderAsync(`${projectFolderPath}/${outputFolderName}`)
       )
     );
@@ -344,7 +344,7 @@ export class OperationBuildCache {
     const tarUtility: TarExecutable | undefined = await _tryGetTarUtility(terminal);
     let restoreSuccess: boolean = false;
     if (tarUtility && localCacheEntryPath) {
-      const logFilePath: string = this._getTarLogFilePath(cacheId, 'untar');
+      const logFilePath: string = this.#getTarLogFilePath(cacheId, 'untar');
       const tarExitCode: number = await tarUtility.tryUntarAsync({
         archivePath: localCacheEntryPath,
         outputFolderPath: projectFolderPath,
@@ -369,12 +369,12 @@ export class OperationBuildCache {
   }
 
   public async trySetCacheEntryAsync(terminal: ITerminal, specifiedCacheId?: string): Promise<boolean> {
-    if (!this._cacheWriteEnabled) {
+    if (!this.#cacheWriteEnabled) {
       // Skip writing local and cloud build caches, without any noise
       return true;
     }
 
-    const cacheId: string | undefined = specifiedCacheId || this._cacheId;
+    const cacheId: string | undefined = specifiedCacheId || this.#cacheId;
     if (!cacheId) {
       terminal.writeWarningLine('Unable to get cache ID. Ensure Git is installed.');
       return false;
@@ -393,14 +393,14 @@ export class OperationBuildCache {
 
     const tarUtility: TarExecutable | undefined = await _tryGetTarUtility(terminal);
     if (tarUtility) {
-      const finalLocalCacheEntryPath: string = this._localBuildCacheProvider.getCacheEntryPath(cacheId);
+      const finalLocalCacheEntryPath: string = this.#localBuildCacheProvider.getCacheEntryPath(cacheId);
       const tempLocalCacheEntryPath: string = _getTempLocalCacheEntryPath(finalLocalCacheEntryPath);
 
-      const logFilePath: string = this._getTarLogFilePath(cacheId, 'tar');
+      const logFilePath: string = this.#getTarLogFilePath(cacheId, 'tar');
       const tarExitCode: number = await tarUtility.tryCreateArchiveFromProjectPathsAsync({
         archivePath: tempLocalCacheEntryPath,
         paths: filesToCache.outputFilePaths,
-        project: this._project,
+        project: this.#project,
         logFilePath
       });
 
@@ -447,25 +447,25 @@ export class OperationBuildCache {
     // the configured CLOUD cache. If the cache is enabled, rush is always allowed to read from and
     // write to the local build cache.
 
-    if (this._cloudBuildCacheProvider?.isCacheWriteAllowed) {
+    if (this.#cloudBuildCacheProvider?.isCacheWriteAllowed) {
       if (!localCacheEntryPath) {
         throw new InternalError('Expected the local cache entry path to be set.');
       }
 
       if (
-        this._useDirectFileTransfersForBuildCache &&
-        this._cloudBuildCacheProvider.tryUploadCacheEntryFromFileAsync
+        this.#useDirectFileTransfersForBuildCache &&
+        this.#cloudBuildCacheProvider.tryUploadCacheEntryFromFileAsync
       ) {
         // Use file-based upload to avoid loading the entire cache entry into memory.
         // The provider reads from the local cache file directly.
-        setCloudCacheEntryPromise = this._cloudBuildCacheProvider.tryUploadCacheEntryFromFileAsync(
+        setCloudCacheEntryPromise = this.#cloudBuildCacheProvider.tryUploadCacheEntryFromFileAsync(
           terminal,
           cacheId,
           localCacheEntryPath
         );
       } else {
         const cacheEntryBuffer: Buffer = await FileSystem.readFileToBufferAsync(localCacheEntryPath);
-        setCloudCacheEntryPromise = this._cloudBuildCacheProvider.trySetCacheEntryBufferAsync(
+        setCloudCacheEntryPromise = this.#cloudBuildCacheProvider.trySetCacheEntryBufferAsync(
           terminal,
           cacheId,
           cacheEntryBuffer
@@ -496,14 +496,14 @@ export class OperationBuildCache {
    *   symbolic link was encountered.
    */
   private async _tryCollectPathsToCacheAsync(terminal: ITerminal): Promise<IPathsToCache | undefined> {
-    const projectFolderPath: string = this._project.projectFolder;
+    const projectFolderPath: string = this.#project.projectFolder;
     const outputFilePaths: string[] = [];
     const queue: [string, string][] = [];
 
     const filteredOutputFolderNames: string[] = [];
 
     let hasSymbolicLinks: boolean = false;
-    const excludeAppleDoubleFiles: boolean = this._excludeAppleDoubleFiles;
+    const excludeAppleDoubleFiles: boolean = this.#excludeAppleDoubleFiles;
 
     // Adds child directories to the queue, files to the path list, and bails on symlinks
     function processChildren(relativePath: string, diskPath: string, children: FolderItem[]): void {
@@ -540,7 +540,7 @@ export class OperationBuildCache {
     }
 
     // Handle declared output folders.
-    for (const outputFolder of this._projectOutputFolderNames) {
+    for (const outputFolder of this.#projectOutputFolderNames) {
       const diskPath: string = `${projectFolderPath}/${outputFolder}`;
       try {
         const children: FolderItem[] = await FileSystem.readFolderItemsAsync(diskPath);
@@ -575,7 +575,7 @@ export class OperationBuildCache {
     };
   }
 
-  private _getTarLogFilePath(cacheId: string, mode: 'tar' | 'untar'): string {
-    return path.join(this._project.projectRushTempFolder, `${cacheId}.${mode}.log`);
+  #getTarLogFilePath(cacheId: string, mode: 'tar' | 'untar'): string {
+    return path.join(this.#project.projectRushTempFolder, `${cacheId}.${mode}.log`);
   }
 }
diff --git a/libraries/rush-lib/src/logic/buildCache/test/OperationBuildCache.test.ts b/libraries/rush-lib/src/logic/buildCache/test/OperationBuildCache.test.ts
index d91554100aa..3431d5eb460 100644
--- a/libraries/rush-lib/src/logic/buildCache/test/OperationBuildCache.test.ts
+++ b/libraries/rush-lib/src/logic/buildCache/test/OperationBuildCache.test.ts
@@ -71,7 +71,7 @@ describe(OperationBuildCache.name, () => {
   describe(OperationBuildCache.getOperationBuildCache.name, () => {
     it('returns an OperationBuildCache with a calculated cacheId value', () => {
       const subject: OperationBuildCache = prepareSubject({});
-      expect(subject['_cacheId']).toMatchInlineSnapshot(
+      expect(subject.cacheId).toMatchInlineSnapshot(
         `"acme-wizard/1926f30e8ed24cb47be89aea39e7efd70fcda075"`
       );
     });
diff --git a/libraries/rush-lib/src/logic/cobuild/CobuildLock.ts b/libraries/rush-lib/src/logic/cobuild/CobuildLock.ts
index 9dbf7114c3d..9eddf8f6954 100644
--- a/libraries/rush-lib/src/logic/cobuild/CobuildLock.ts
+++ b/libraries/rush-lib/src/logic/cobuild/CobuildLock.ts
@@ -43,7 +43,7 @@ export class CobuildLock {
   public readonly cobuildConfiguration: CobuildConfiguration;
   public readonly operationBuildCache: OperationBuildCache;
 
-  private _cobuildContext: ICobuildContext;
+  #cobuildContext: ICobuildContext;
 
   public constructor(options: ICobuildLockOptions) {
     const {
@@ -75,7 +75,7 @@ export class CobuildLock {
     // Example: cobuild:completed:<contextId>:<cacheId>
     const completedStateKey: string = ['cobuild', 'completed', contextId, cacheId].join(KEY_SEPARATOR);
 
-    this._cobuildContext = {
+    this.#cobuildContext = {
       contextId,
       clusterId,
       runnerId,
@@ -91,20 +91,20 @@ export class CobuildLock {
   public async setCompletedStateAsync(state: ICobuildCompletedState): Promise<void> {
     await this.cobuildConfiguration
       .getCobuildLockProvider()
-      .setCompletedStateAsync(this._cobuildContext, state);
+      .setCompletedStateAsync(this.#cobuildContext, state);
   }
 
   public async getCompletedStateAsync(): Promise<ICobuildCompletedState | undefined> {
     const state: ICobuildCompletedState | undefined = await this.cobuildConfiguration
       .getCobuildLockProvider()
-      .getCompletedStateAsync(this._cobuildContext);
+      .getCompletedStateAsync(this.#cobuildContext);
     return state;
   }
 
   public async tryAcquireLockAsync(): Promise<boolean> {
     const acquireLockResult: boolean = await this.cobuildConfiguration
       .getCobuildLockProvider()
-      .acquireLockAsync(this._cobuildContext);
+      .acquireLockAsync(this.#cobuildContext);
     if (acquireLockResult) {
       // renew the lock in a redundant way in case of losing the lock
       await this.renewLockAsync();
@@ -113,10 +113,10 @@ export class CobuildLock {
   }
 
   public async renewLockAsync(): Promise<void> {
-    await this.cobuildConfiguration.getCobuildLockProvider().renewLockAsync(this._cobuildContext);
+    await this.cobuildConfiguration.getCobuildLockProvider().renewLockAsync(this.#cobuildContext);
   }
 
   public get cobuildContext(): ICobuildContext {
-    return this._cobuildContext;
+    return this.#cobuildContext;
   }
 }
diff --git a/libraries/rush-lib/src/logic/cobuild/DisjointSet.ts b/libraries/rush-lib/src/logic/cobuild/DisjointSet.ts
index 3a33aef59ae..6b41149b8e1 100644
--- a/libraries/rush-lib/src/logic/cobuild/DisjointSet.ts
+++ b/libraries/rush-lib/src/logic/cobuild/DisjointSet.ts
@@ -7,101 +7,101 @@ import { InternalError } from '@rushstack/node-core-library';
  * A disjoint set data structure
  */
 export class DisjointSet<T extends object> {
-  private _forest: Set<T>;
-  private _parentMap: Map<T, T>;
-  private _sizeMap: Map<T, number>;
-  private _setByElement: Map<T, Set<T>> | undefined;
+  #forest: Set<T>;
+  #parentMap: Map<T, T>;
+  #sizeMap: Map<T, number>;
+  #setByElement: Map<T, Set<T>> | undefined;
 
   public constructor() {
-    this._forest = new Set<T>();
-    this._parentMap = new Map<T, T>();
-    this._sizeMap = new Map<T, number>();
-    this._setByElement = new Map<T, Set<T>>();
+    this.#forest = new Set<T>();
+    this.#parentMap = new Map<T, T>();
+    this.#sizeMap = new Map<T, number>();
+    this.#setByElement = new Map<T, Set<T>>();
   }
 
   public destroy(): void {
-    this._forest.clear();
-    this._parentMap.clear();
-    this._sizeMap.clear();
-    this._setByElement?.clear();
+    this.#forest.clear();
+    this.#parentMap.clear();
+    this.#sizeMap.clear();
+    this.#setByElement?.clear();
   }
 
   /**
    * Adds a new set containing specific object
    */
   public add(x: T): void {
-    if (this._forest.has(x)) {
+    if (this.#forest.has(x)) {
       return;
     }
 
-    this._forest.add(x);
-    this._parentMap.set(x, x);
-    this._sizeMap.set(x, 1);
-    this._setByElement = undefined;
+    this.#forest.add(x);
+    this.#parentMap.set(x, x);
+    this.#sizeMap.set(x, 1);
+    this.#setByElement = undefined;
   }
 
   /**
    * Unions the sets that contain two objects
    */
   public union(a: T, b: T): void {
-    let x: T = this._find(a);
-    let y: T = this._find(b);
+    let x: T = this.#find(a);
+    let y: T = this.#find(b);
 
     if (x === y) {
       // x and y are already in the same set
       return;
     }
 
-    const xSize: number = this._getSize(x);
-    const ySize: number = this._getSize(y);
+    const xSize: number = this.#getSize(x);
+    const ySize: number = this.#getSize(y);
     if (xSize < ySize) {
       const t: T = x;
       x = y;
       y = t;
     }
-    this._parentMap.set(y, x);
-    this._sizeMap.set(x, xSize + ySize);
-    this._setByElement = undefined;
+    this.#parentMap.set(y, x);
+    this.#sizeMap.set(x, xSize + ySize);
+    this.#setByElement = undefined;
   }
 
   public getAllSets(): Iterable<Set<T>> {
-    if (this._setByElement === undefined) {
-      this._setByElement = new Map<T, Set<T>>();
+    if (this.#setByElement === undefined) {
+      this.#setByElement = new Map<T, Set<T>>();
 
-      for (const element of this._forest) {
-        const root: T = this._find(element);
-        let set: Set<T> | undefined = this._setByElement.get(root);
+      for (const element of this.#forest) {
+        const root: T = this.#find(element);
+        let set: Set<T> | undefined = this.#setByElement.get(root);
         if (set === undefined) {
           set = new Set<T>();
-          this._setByElement.set(root, set);
+          this.#setByElement.set(root, set);
         }
         set.add(element);
       }
     }
-    return this._setByElement.values();
+    return this.#setByElement.values();
   }
 
   /**
    * Returns true if x and y are in the same set
    */
   public isConnected(x: T, y: T): boolean {
-    return this._find(x) === this._find(y);
+    return this.#find(x) === this.#find(y);
   }
 
-  private _find(a: T): T {
+  #find(a: T): T {
     let x: T = a;
-    let parent: T = this._getParent(x);
+    let parent: T = this.#getParent(x);
     while (parent !== x) {
-      parent = this._getParent(parent);
-      this._parentMap.set(x, parent);
+      parent = this.#getParent(parent);
+      this.#parentMap.set(x, parent);
       x = parent;
-      parent = this._getParent(x);
+      parent = this.#getParent(x);
     }
     return x;
   }
 
-  private _getParent(x: T): T {
-    const parent: T | undefined = this._parentMap.get(x);
+  #getParent(x: T): T {
+    const parent: T | undefined = this.#parentMap.get(x);
     if (parent === undefined) {
       // This should not happen
       throw new InternalError(`Can not find parent`);
@@ -109,8 +109,8 @@ export class DisjointSet<T extends object> {
     return parent;
   }
 
-  private _getSize(x: T): number {
-    const size: number | undefined = this._sizeMap.get(x);
+  #getSize(x: T): number {
+    const size: number | undefined = this.#sizeMap.get(x);
     if (size === undefined) {
       // This should not happen
       throw new InternalError(`Can not get size`);
diff --git a/libraries/rush-lib/src/logic/incremental/InputsSnapshot.ts b/libraries/rush-lib/src/logic/incremental/InputsSnapshot.ts
index c0c61334f33..4fa4d1b0ac2 100644
--- a/libraries/rush-lib/src/logic/incremental/InputsSnapshot.ts
+++ b/libraries/rush-lib/src/logic/incremental/InputsSnapshot.ts
@@ -198,26 +198,26 @@ export class InputsSnapshot implements IInputsSnapshot {
   /**
    * The metadata for each project. This is a superset of the information in `projectMap` and includes caching of queries.
    */
-  private readonly _projectMetadataMap: Map<
+  readonly #projectMetadataMap: Map<
     IRushConfigurationProjectForSnapshot,
     IInternalInputsSnapshotProjectMetadata
   >;
   /**
    * Hashes of files to be included in all result sets.
    */
-  private readonly _globalAdditionalHashes: ReadonlyMap<string, string> | undefined;
+  readonly #globalAdditionalHashes: ReadonlyMap<string, string> | undefined;
   /**
    * Hashes for files selected by `dependsOnAdditionalFiles`.
    */
-  private readonly _additionalHashes: ReadonlyMap<string, string> | undefined;
+  readonly #additionalHashes: ReadonlyMap<string, string> | undefined;
   /**
    * The environment to use for `dependsOnEnvVars`.
    */
-  private readonly _environment: Record<string, string | undefined>;
+  readonly #environment: Record<string, string | undefined>;
   /**
    * Pre-computed Node.js version strings at each granularity level for `dependsOnNodeVersion`.
    */
-  private readonly _nodeVersionByGranularity: Readonly<Record<NodeVersionGranularity, string>>;
+  readonly #nodeVersionByGranularity: Readonly<Record<NodeVersionGranularity, string>>;
 
   /**
    *
@@ -283,13 +283,13 @@ export class InputsSnapshot implements IInputsSnapshot {
       Sort.sortMapKeys(record.hashes);
     }
 
-    this._projectMetadataMap = projectMetadataMap;
-    this._additionalHashes = additionalHashes;
-    this._globalAdditionalHashes = globalAdditionalHashes;
+    this.#projectMetadataMap = projectMetadataMap;
+    this.#additionalHashes = additionalHashes;
+    this.#globalAdditionalHashes = globalAdditionalHashes;
     // Snapshot the environment so that queries are not impacted by when they happen
-    this._environment = environment;
+    this.#environment = environment;
     // Parse Node.js version once so it doesn't need to be re-parsed per operation
-    this._nodeVersionByGranularity = _parseNodeVersion(nodeVersion);
+    this.#nodeVersionByGranularity = _parseNodeVersion(nodeVersion);
     this.hashes = hashes;
     this.hasUncommittedChanges = hasUncommittedChanges;
     this.rootDirectory = rootDir;
@@ -302,7 +302,7 @@ export class InputsSnapshot implements IInputsSnapshot {
     project: IRushConfigurationProjectForSnapshot,
     operationName?: string
   ): ReadonlyMap<string, string> {
-    const record: IInternalInputsSnapshotProjectMetadata | undefined = this._projectMetadataMap.get(project);
+    const record: IInternalInputsSnapshotProjectMetadata | undefined = this.#projectMetadataMap.get(project);
     if (!record) {
       throw new InternalError(`No information available for project at ${project.projectFolder}`);
     }
@@ -336,13 +336,13 @@ export class InputsSnapshot implements IInputsSnapshot {
         if (additionalFilesForOperation) {
           // Sort the additional files to ensure deterministic hash computation
           const sortedAdditionalFiles: string[] = Array.from(additionalFilesForOperation).sort();
-          for (const [filePath, hash] of this._resolveHashes(sortedAdditionalFiles)) {
+          for (const [filePath, hash] of this.#resolveHashes(sortedAdditionalFiles)) {
             hashes.set(filePath, hash);
           }
         }
       }
 
-      const { _globalAdditionalHashes: globalAdditionalHashes } = this;
+      const globalAdditionalHashes: ReadonlyMap<string, string> | undefined = this.#globalAdditionalHashes;
       if (globalAdditionalHashes) {
         for (const [file, hash] of globalAdditionalHashes) {
           record.hashes.set(file, hash);
@@ -379,7 +379,7 @@ export class InputsSnapshot implements IInputsSnapshot {
     project: IRushConfigurationProjectForSnapshot,
     operationName?: string
   ): string {
-    const record: IInternalInputsSnapshotProjectMetadata | undefined = this._projectMetadataMap.get(project);
+    const record: IInternalInputsSnapshotProjectMetadata | undefined = this.#projectMetadataMap.get(project);
     if (!record) {
       throw new Error(`No information available for project at ${project.projectFolder}`);
     }
@@ -403,14 +403,14 @@ export class InputsSnapshot implements IInputsSnapshot {
             // As long as we enumerate environment variables in a consistent order, we will get a stable hash.
             // Changing the order in rush-project.json will change the hash anyway since the file contents are part of the hash.
             for (const envVar of dependsOnEnvVars) {
-              hasher.update(`${hashDelimiter}$${envVar}=${this._environment[envVar] || ''}`);
+              hasher.update(`${hashDelimiter}$${envVar}=${this.#environment[envVar] || ''}`);
             }
           }
 
           if (dependsOnNodeVersion) {
             const granularity: NodeVersionGranularity =
               dependsOnNodeVersion === true ? 'patch' : dependsOnNodeVersion;
-            hasher.update(`${hashDelimiter}nodeVersion=${this._nodeVersionByGranularity[granularity]}`);
+            hasher.update(`${hashDelimiter}nodeVersion=${this.#nodeVersionByGranularity[granularity]}`);
           }
 
           if (outputFolderNames) {
@@ -432,11 +432,12 @@ export class InputsSnapshot implements IInputsSnapshot {
     return hash;
   }
 
-  private *_resolveHashes(filePaths: Iterable<string>): Generator<[string, string]> {
-    const { hashes, _additionalHashes } = this;
+  *#resolveHashes(filePaths: Iterable<string>): Generator<[string, string]> {
+    const { hashes } = this;
+    const additionalHashes: ReadonlyMap<string, string> | undefined = this.#additionalHashes;
 
     for (const filePath of filePaths) {
-      const hash: string | undefined = hashes.get(filePath) ?? _additionalHashes?.get(filePath);
+      const hash: string | undefined = hashes.get(filePath) ?? additionalHashes?.get(filePath);
       if (!hash) {
         throw new Error(`Could not find hash for file path "${filePath}"`);
       }
diff --git a/libraries/rush-lib/src/logic/installManager/RushInstallManager.ts b/libraries/rush-lib/src/logic/installManager/RushInstallManager.ts
index ff64f638de6..5114cb91057 100644
--- a/libraries/rush-lib/src/logic/installManager/RushInstallManager.ts
+++ b/libraries/rush-lib/src/logic/installManager/RushInstallManager.ts
@@ -61,7 +61,7 @@ declare module 'tar' {
  * This class implements common logic between "rush install" and "rush update".
  */
 export class RushInstallManager extends BaseInstallManager {
-  private _tempProjectHelper: TempProjectHelper;
+  #tempProjectHelper: TempProjectHelper;
 
   public constructor(
     rushConfiguration: RushConfiguration,
@@ -70,7 +70,7 @@ export class RushInstallManager extends BaseInstallManager {
     options: IInstallManagerOptions
   ) {
     super(rushConfiguration, rushGlobalFolder, purgeManager, options);
-    this._tempProjectHelper = new TempProjectHelper(
+    this.#tempProjectHelper = new TempProjectHelper(
       this.rushConfiguration,
       rushConfiguration.defaultSubspace
     );
@@ -144,7 +144,7 @@ export class RushInstallManager extends BaseInstallManager {
         }
       });
 
-      if (this._findMissingTempProjects(shrinkwrapFile)) {
+      if (this.#findMissingTempProjects(shrinkwrapFile)) {
         // If any Rush project's tarball is missing from the shrinkwrap file, then we need to update
         // the shrinkwrap file.
         shrinkwrapIsUpToDate = false;
@@ -182,7 +182,7 @@ export class RushInstallManager extends BaseInstallManager {
       const packageJson: PackageJsonEditor = rushProject.packageJsonEditor;
 
       // Example: "C:\MyRepo\common\temp\projects\my-project-2.tgz"
-      const tarballFile: string = this._tempProjectHelper.getTarballFilePath(rushProject);
+      const tarballFile: string = this.#tempProjectHelper.getTarballFilePath(rushProject);
 
       // Example: dependencies["@rush-temp/my-project-2"] = "file:./projects/my-project-2.tgz"
       commonDependencies.set(
@@ -203,7 +203,7 @@ export class RushInstallManager extends BaseInstallManager {
       // These can be regular, optional, or peer dependencies (but NOT dev dependencies).
       // (A given packageName will never appear more than once in this list.)
       for (const dependency of packageJson.dependencyList) {
-        if (this.options.fullUpgrade && this._revertWorkspaceNotation(dependency)) {
+        if (this.options.fullUpgrade && this.#revertWorkspaceNotation(dependency)) {
           shrinkwrapIsUpToDate = false;
         }
 
@@ -219,7 +219,7 @@ export class RushInstallManager extends BaseInstallManager {
       }
 
       for (const dependency of packageJson.devDependencyList) {
-        if (this.options.fullUpgrade && this._revertWorkspaceNotation(dependency)) {
+        if (this.options.fullUpgrade && this.#revertWorkspaceNotation(dependency)) {
           shrinkwrapIsUpToDate = false;
         }
 
@@ -282,7 +282,7 @@ export class RushInstallManager extends BaseInstallManager {
       }
 
       // Example: "C:\MyRepo\common\temp\projects\my-project-2"
-      const tempProjectFolder: string = this._tempProjectHelper.getTempProjectFolder(rushProject);
+      const tempProjectFolder: string = this.#tempProjectHelper.getTempProjectFolder(rushProject);
 
       // Example: "C:\MyRepo\common\temp\projects\my-project-2\package.json"
       const tempPackageJsonFilename: string = path.join(tempProjectFolder, FileConstants.PackageJson);
@@ -319,7 +319,7 @@ export class RushInstallManager extends BaseInstallManager {
           JsonFile.save(tempPackageJson, tempPackageJsonFilename);
 
           // Delete the existing tarball and create a new one
-          this._tempProjectHelper.createTempProjectTarball(rushProject);
+          this.#tempProjectHelper.createTempProjectTarball(rushProject);
 
           // eslint-disable-next-line no-console
           console.log(`Updating ${tarballFile}`);
@@ -340,7 +340,7 @@ export class RushInstallManager extends BaseInstallManager {
         this.rushConfiguration.experimentsConfiguration.configuration.usePnpmFrozenLockfileForRushInstall
       ) {
         const pnpmShrinkwrapFile: PnpmShrinkwrapFile = shrinkwrapFile as PnpmShrinkwrapFile;
-        const tarballIntegrityValid: boolean = await this._validateRushProjectTarballIntegrityAsync(
+        const tarballIntegrityValid: boolean = await this.#validateRushProjectTarballIntegrityAsync(
           pnpmShrinkwrapFile,
           rushProject
         );
@@ -396,7 +396,7 @@ export class RushInstallManager extends BaseInstallManager {
     return { shrinkwrapIsUpToDate, shrinkwrapWarnings };
   }
 
-  private _revertWorkspaceNotation(dependency: PackageJsonDependency): boolean {
+  #revertWorkspaceNotation(dependency: PackageJsonDependency): boolean {
     const specifier: DependencySpecifier = DependencySpecifier.parseWithCache(
       dependency.name,
       dependency.version
@@ -420,7 +420,7 @@ export class RushInstallManager extends BaseInstallManager {
     return true;
   }
 
-  private async _validateRushProjectTarballIntegrityAsync(
+  async #validateRushProjectTarballIntegrityAsync(
     shrinkwrapFile: PnpmShrinkwrapFile | undefined,
     rushProject: RushConfigurationProject
   ): Promise<boolean> {
@@ -435,7 +435,7 @@ export class RushInstallManager extends BaseInstallManager {
       const parentShrinkwrapEntry: IPnpmShrinkwrapDependencyYaml =
         shrinkwrapFile.getShrinkwrapEntryFromTempProjectDependencyKey(tempProjectDependencyKey)!;
       const newIntegrity: string = (
-        await ssri.fromStream(fs.createReadStream(this._tempProjectHelper.getTarballFilePath(rushProject)))
+        await ssri.fromStream(fs.createReadStream(this.#tempProjectHelper.getTarballFilePath(rushProject)))
       ).toString();
 
       if (!parentShrinkwrapEntry.resolution || parentShrinkwrapEntry.resolution.integrity !== newIntegrity) {
@@ -464,7 +464,7 @@ export class RushInstallManager extends BaseInstallManager {
     // Example: "C:\MyRepo\common\temp\projects\my-project-2.tgz"
     potentiallyChangedFiles.push(
       ...this.rushConfiguration.projects.map((x) => {
-        return this._tempProjectHelper.getTarballFilePath(x);
+        return this.#tempProjectHelper.getTarballFilePath(x);
       })
     );
 
@@ -479,7 +479,7 @@ export class RushInstallManager extends BaseInstallManager {
     // This ensures that any existing tarballs with older header bits will be regenerated.
     // It is safe to assume that temp project pacakge.jsons already exist.
     for (const rushProject of this.rushConfiguration.projects) {
-      this._tempProjectHelper.createTempProjectTarball(rushProject);
+      this.#tempProjectHelper.createTempProjectTarball(rushProject);
     }
 
     // NOTE: The PNPM store is supposed to be transactionally safe, so we don't delete it automatically.
@@ -653,7 +653,7 @@ export class RushInstallManager extends BaseInstallManager {
       // eslint-disable-next-line no-console
       console.log('"npm shrinkwrap" completed\n');
 
-      await this._fixupNpm5RegressionAsync();
+      await this.#fixupNpm5RegressionAsync();
     }
   }
 
@@ -683,7 +683,7 @@ export class RushInstallManager extends BaseInstallManager {
    * Our workaround is to rewrite the package.json files for each of the @rush-temp projects
    * in the node_modules folder, after "npm install" completes.
    */
-  private async _fixupNpm5RegressionAsync(): Promise<void> {
+  async #fixupNpm5RegressionAsync(): Promise<void> {
     const pathToDeleteWithoutStar: string = path.join(
       this.rushConfiguration.commonTempFolder,
       'node_modules',
@@ -725,7 +725,7 @@ export class RushInstallManager extends BaseInstallManager {
    *
    * @returns true if orphans were found, or false if everything is okay
    */
-  private _findMissingTempProjects(shrinkwrapFile: BaseShrinkwrapFile): boolean {
+  #findMissingTempProjects(shrinkwrapFile: BaseShrinkwrapFile): boolean {
     const tempProjectNames: Set<string> = new Set(shrinkwrapFile.getTempProjectNames());
 
     for (const rushProject of this.rushConfiguration.projects) {
diff --git a/libraries/rush-lib/src/logic/npm/NpmLinkManager.ts b/libraries/rush-lib/src/logic/npm/NpmLinkManager.ts
index 97e4098d7ef..a3bf7f8a4c0 100644
--- a/libraries/rush-lib/src/logic/npm/NpmLinkManager.ts
+++ b/libraries/rush-lib/src/logic/npm/NpmLinkManager.ts
@@ -45,7 +45,7 @@ export class NpmLinkManager extends BaseLinkManager {
     for (const rushProject of this._rushConfiguration.projects) {
       // eslint-disable-next-line no-console
       console.log(`\nLINKING: ${rushProject.packageName}`);
-      await this._linkProjectAsync(rushProject, commonRootPackage, commonPackageLookup);
+      await this.#linkProjectAsync(rushProject, commonRootPackage, commonPackageLookup);
     }
   }
 
@@ -55,7 +55,7 @@ export class NpmLinkManager extends BaseLinkManager {
    * @param commonRootPackage   The common/temp/package.json package
    * @param commonPackageLookup A dictionary for finding packages under common/temp/node_modules
    */
-  private async _linkProjectAsync(
+  async #linkProjectAsync(
     project: RushConfigurationProject,
     commonRootPackage: NpmPackage,
     commonPackageLookup: PackageLookup
diff --git a/libraries/rush-lib/src/logic/npm/NpmShrinkwrapFile.ts b/libraries/rush-lib/src/logic/npm/NpmShrinkwrapFile.ts
index b0880d98b7b..6555e361389 100644
--- a/libraries/rush-lib/src/logic/npm/NpmShrinkwrapFile.ts
+++ b/libraries/rush-lib/src/logic/npm/NpmShrinkwrapFile.ts
@@ -24,21 +24,21 @@ interface INpmShrinkwrapJson {
 
 export class NpmShrinkwrapFile extends BaseShrinkwrapFile {
   public readonly isWorkspaceCompatible: boolean;
-  private _shrinkwrapJson: INpmShrinkwrapJson;
+  #shrinkwrapJson: INpmShrinkwrapJson;
 
   private constructor(shrinkwrapJson: INpmShrinkwrapJson) {
     super();
-    this._shrinkwrapJson = shrinkwrapJson;
+    this.#shrinkwrapJson = shrinkwrapJson;
 
     // Normalize the data
-    if (!this._shrinkwrapJson.version) {
-      this._shrinkwrapJson.version = '';
+    if (!this.#shrinkwrapJson.version) {
+      this.#shrinkwrapJson.version = '';
     }
-    if (!this._shrinkwrapJson.name) {
-      this._shrinkwrapJson.name = '';
+    if (!this.#shrinkwrapJson.name) {
+      this.#shrinkwrapJson.name = '';
     }
-    if (!this._shrinkwrapJson.dependencies) {
-      this._shrinkwrapJson.dependencies = {};
+    if (!this.#shrinkwrapJson.dependencies) {
+      this.#shrinkwrapJson.dependencies = {};
     }
 
     // Workspaces not supported in NPM
@@ -68,17 +68,17 @@ export class NpmShrinkwrapFile extends BaseShrinkwrapFile {
   }
 
   public override getTempProjectNames(): ReadonlyArray<string> {
-    return this._getTempProjectNames(this._shrinkwrapJson.dependencies);
+    return this._getTempProjectNames(this.#shrinkwrapJson.dependencies);
   }
 
   protected override serialize(): string {
-    return JsonFile.stringify(this._shrinkwrapJson);
+    return JsonFile.stringify(this.#shrinkwrapJson);
   }
 
   protected override getTopLevelDependencyVersion(dependencyName: string): DependencySpecifier | undefined {
     // First, check under tempProjectName, as this is the first place we look during linking.
     const dependencyJson: INpmShrinkwrapDependencyJson | undefined = NpmShrinkwrapFile.tryGetValue(
-      this._shrinkwrapJson.dependencies,
+      this.#shrinkwrapJson.dependencies,
       dependencyName
     );
 
@@ -102,7 +102,7 @@ export class NpmShrinkwrapFile extends BaseShrinkwrapFile {
     let dependencyJson: INpmShrinkwrapDependencyJson | undefined = undefined;
 
     const tempDependency: INpmShrinkwrapDependencyJson | undefined = NpmShrinkwrapFile.tryGetValue(
-      this._shrinkwrapJson.dependencies,
+      this.#shrinkwrapJson.dependencies,
       tempProjectName
     );
     if (tempDependency && tempDependency.dependencies) {
diff --git a/libraries/rush-lib/src/logic/operations/AsyncOperationQueue.ts b/libraries/rush-lib/src/logic/operations/AsyncOperationQueue.ts
index 6602ca74485..035eb53395a 100644
--- a/libraries/rush-lib/src/logic/operations/AsyncOperationQueue.ts
+++ b/libraries/rush-lib/src/logic/operations/AsyncOperationQueue.ts
@@ -17,19 +17,19 @@ import { RushConstants } from '../RushConstants';
 export class AsyncOperationQueue
   implements AsyncIterable<OperationExecutionRecord>, AsyncIterator<OperationExecutionRecord>
 {
-  private readonly _queue: OperationExecutionRecord[];
-  private readonly _pendingIterators: ((result: IteratorResult<OperationExecutionRecord>) => void)[];
-  private readonly _totalOperations: number;
-  private readonly _completedOperations: Set<OperationExecutionRecord>;
+  readonly #queue: OperationExecutionRecord[];
+  readonly #pendingIterators: ((result: IteratorResult<OperationExecutionRecord>) => void)[];
+  readonly #totalOperations: number;
+  readonly #completedOperations: Set<OperationExecutionRecord>;
 
   /**
    * Tracks how many times each operation has been assigned to an execution slot.
    * Operations that have been assigned more times (e.g. cobuild retries) are sorted
    * after operations with fewer attempts, so untried work is preferred.
    */
-  private readonly _numberOfTimesQueuedByOperation: Map<OperationExecutionRecord, number>;
+  readonly #numberOfTimesQueuedByOperation: Map<OperationExecutionRecord, number>;
 
-  private _isDone: boolean;
+  #isDone: boolean;
 
   /**
    * @param operations - The set of operations to be executed
@@ -39,12 +39,12 @@ export class AsyncOperationQueue
    *   - Returning 0 indicates no preference.
    */
   public constructor(operations: Iterable<OperationExecutionRecord>, sortFn: IOperationSortFunction) {
-    this._queue = computeTopologyAndSort(operations, sortFn);
-    this._pendingIterators = [];
-    this._totalOperations = this._queue.length;
-    this._isDone = false;
-    this._completedOperations = new Set<OperationExecutionRecord>();
-    this._numberOfTimesQueuedByOperation = new Map();
+    this.#queue = computeTopologyAndSort(operations, sortFn);
+    this.#pendingIterators = [];
+    this.#totalOperations = this.#queue.length;
+    this.#isDone = false;
+    this.#completedOperations = new Set<OperationExecutionRecord>();
+    this.#numberOfTimesQueuedByOperation = new Map();
   }
 
   /**
@@ -52,7 +52,8 @@ export class AsyncOperationQueue
    * @see {AsyncIterator}
    */
   public next(): Promise<IteratorResult<OperationExecutionRecord>> {
-    const { _pendingIterators: waitingIterators } = this;
+    const waitingIterators: Array<(result: IteratorResult<OperationExecutionRecord>) => void> =
+      this.#pendingIterators;
 
     const promise: Promise<IteratorResult<OperationExecutionRecord>> = new Promise(
       (resolve: (result: IteratorResult<OperationExecutionRecord>) => void) => {
@@ -70,8 +71,8 @@ export class AsyncOperationQueue
    * If all operations are completed, set the queue to done, resolve all pending iterators in next cycle.
    */
   public complete(record: OperationExecutionRecord): void {
-    this._completedOperations.add(record);
-    this._numberOfTimesQueuedByOperation.delete(record);
+    this.#completedOperations.add(record);
+    this.#numberOfTimesQueuedByOperation.delete(record);
 
     // Apply status changes to direct dependents
     if (record.status !== OperationStatus.Failure && record.status !== OperationStatus.Blocked) {
@@ -90,8 +91,8 @@ export class AsyncOperationQueue
 
     this.assignOperations();
 
-    if (this._completedOperations.size === this._totalOperations) {
-      this._isDone = true;
+    if (this.#completedOperations.size === this.#totalOperations) {
+      this.#isDone = true;
     }
   }
 
@@ -100,11 +101,10 @@ export class AsyncOperationQueue
    * if the caller does not update operation dependencies prior to calling `next()`, may need to be invoked manually.
    */
   public assignOperations(): void {
-    const {
-      _queue: queue,
-      _pendingIterators: waitingIterators,
-      _numberOfTimesQueuedByOperation: timesQueued
-    } = this;
+    const queue: OperationExecutionRecord[] = this.#queue;
+    const waitingIterators: Array<(result: IteratorResult<OperationExecutionRecord>) => void> =
+      this.#pendingIterators;
+    const timesQueued: Map<OperationExecutionRecord, number> = this.#numberOfTimesQueuedByOperation;
 
     const readyOperations: OperationExecutionRecord[] = [];
 
@@ -164,10 +164,10 @@ export class AsyncOperationQueue
 
     // Since items only get removed from the queue when they have a final status, this should be safe.
     if (queue.length === 0) {
-      this._isDone = true;
+      this.#isDone = true;
     }
 
-    if (this._isDone) {
+    if (this.#isDone) {
       for (const resolveAsyncIterator of waitingIterators.splice(0)) {
         resolveAsyncIterator({
           value: undefined,
diff --git a/libraries/rush-lib/src/logic/operations/BuildPlanPlugin.ts b/libraries/rush-lib/src/logic/operations/BuildPlanPlugin.ts
index dce4ed3785a..cc17d508895 100644
--- a/libraries/rush-lib/src/logic/operations/BuildPlanPlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/BuildPlanPlugin.ts
@@ -34,14 +34,14 @@ interface ICobuildPlan {
 }
 
 export class BuildPlanPlugin implements IPhasedCommandPlugin {
-  private readonly _terminal: ITerminal;
+  readonly #terminal: ITerminal;
 
   public constructor(terminal: ITerminal) {
-    this._terminal = terminal;
+    this.#terminal = terminal;
   }
 
   public apply(hooks: PhasedCommandHooks): void {
-    const terminal: ITerminal = this._terminal;
+    const terminal: ITerminal = this.#terminal;
 
     hooks.onGraphCreatedAsync.tap(PLUGIN_NAME, (graph: IOperationGraph, context: IOperationGraphContext) => {
       graph.hooks.configureIteration.tap(PLUGIN_NAME, (currentStates, lastStates, iterationOptions) => {
diff --git a/libraries/rush-lib/src/logic/operations/CacheableOperationPlugin.ts b/libraries/rush-lib/src/logic/operations/CacheableOperationPlugin.ts
index 6f254f52fc6..6980355c88f 100644
--- a/libraries/rush-lib/src/logic/operations/CacheableOperationPlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/CacheableOperationPlugin.ts
@@ -98,12 +98,12 @@ interface ITryGetLogOnlyOperationBuildCacheOptions
 }
 
 export class CacheableOperationPlugin implements IPhasedCommandPlugin {
-  private _buildCacheContextByOperation: Map<Operation, IOperationBuildCacheContext> = new Map();
+  #buildCacheContextByOperation: Map<Operation, IOperationBuildCacheContext> = new Map();
 
-  private readonly _options: ICacheableOperationPluginOptions;
+  readonly #options: ICacheableOperationPluginOptions;
 
   public constructor(options: ICacheableOperationPluginOptions) {
-    this._options = options;
+    this.#options = options;
   }
 
   public apply(hooks: PhasedCommandHooks): void {
@@ -113,7 +113,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
       cobuildConfiguration,
       excludeAppleDoubleFiles,
       useDirectFileTransfersForBuildCache
-    } = this._options;
+    } = this.#options;
 
     hooks.onGraphCreatedAsync.tap(PLUGIN_NAME, (graph: IOperationGraph, context: IOperationGraphContext) => {
       graph.hooks.beforeExecuteIterationAsync.tap(
@@ -187,11 +187,11 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
               isCacheReadAttempted: false
             };
             // Upstream runners may mutate the property of build cache context for downstream runners
-            this._buildCacheContextByOperation.set(operation, buildCacheContext);
+            this.#buildCacheContextByOperation.set(operation, buildCacheContext);
           }
 
           if (disjointSet) {
-            clusterOperations(disjointSet, this._buildCacheContextByOperation);
+            clusterOperations(disjointSet, this.#buildCacheContextByOperation);
             for (const operationSet of disjointSet.getAllSets()) {
               if (cobuildConfiguration?.cobuildFeatureEnabled && cobuildConfiguration.cobuildContextId) {
                 // Get a deterministic ordered array of operations, which is important to get a deterministic cluster id.
@@ -214,7 +214,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
                 // Assign same cluster id to all operations in the same cluster.
                 for (const record of groupedOperations) {
                   const buildCacheContext: IOperationBuildCacheContext =
-                    this._getBuildCacheContextByOperationOrThrow(record);
+                    this.#getBuildCacheContextByOperationOrThrow(record);
                   buildCacheContext.cobuildClusterId = cobuildClusterId;
                 }
               }
@@ -228,12 +228,12 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
         async (
           runnerContext: IOperationRunnerContext & IOperationExecutionResult
         ): Promise<OperationStatus | undefined> => {
-          if (this._buildCacheContextByOperation.size === 0) {
+          if (this.#buildCacheContextByOperation.size === 0) {
             return;
           }
 
           const buildCacheContext: IOperationBuildCacheContext | undefined =
-            this._getBuildCacheContextByOperation(runnerContext.operation);
+            this.#getBuildCacheContextByOperation(runnerContext.operation);
 
           if (!buildCacheContext) {
             return;
@@ -260,7 +260,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
             ) {
               // The writable does not exist or has been closed, re-create one
               // eslint-disable-next-line require-atomic-updates
-              buildCacheContext.buildCacheTerminal = await this._createBuildCacheTerminalAsync({
+              buildCacheContext.buildCacheTerminal = await this.#createBuildCacheTerminalAsync({
                 record,
                 buildCacheContext,
                 buildCacheEnabled: buildCacheConfiguration?.buildCacheEnabled,
@@ -273,7 +273,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
 
             const buildCacheTerminal: ITerminal = buildCacheContext.buildCacheTerminal;
 
-            let operationBuildCache: OperationBuildCache | undefined = this._tryGetOperationBuildCache({
+            let operationBuildCache: OperationBuildCache | undefined = this.#tryGetOperationBuildCache({
               buildCacheContext,
               buildCacheConfiguration,
               terminal: buildCacheTerminal,
@@ -292,7 +292,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
               ) {
                 // When the leaf project log only is allowed and the leaf project is build cache "disabled", try to get
                 // a log files only project build cache
-                operationBuildCache = await this._tryGetLogOnlyOperationBuildCacheAsync({
+                operationBuildCache = await this.#tryGetLogOnlyOperationBuildCacheAsync({
                   buildCacheConfiguration,
                   cobuildConfiguration,
                   buildCacheContext,
@@ -312,7 +312,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
                 }
               }
 
-              cobuildLock = await this._tryGetCobuildLockAsync({
+              cobuildLock = await this.#tryGetCobuildLockAsync({
                 buildCacheContext,
                 operationBuildCache,
                 cobuildConfiguration,
@@ -448,7 +448,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
           }
 
           const buildCacheContext: IOperationBuildCacheContext | undefined =
-            this._getBuildCacheContextByOperation(operation);
+            this.#getBuildCacheContextByOperation(operation);
 
           if (!buildCacheContext) {
             return;
@@ -549,7 +549,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
         (record: IOperationRunnerContext & IOperationExecutionResult): void => {
           const { operation } = record;
           const buildCacheContext: IOperationBuildCacheContext | undefined =
-            this._buildCacheContextByOperation.get(operation);
+            this.#buildCacheContextByOperation.get(operation);
           // Status changes to direct dependents
           let blockCacheWrite: boolean = !buildCacheContext?.isCacheWriteAllowed;
 
@@ -565,7 +565,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
           if (blockCacheWrite) {
             for (const consumer of operation.consumers) {
               const consumerBuildCacheContext: IOperationBuildCacheContext | undefined =
-                this._getBuildCacheContextByOperation(consumer);
+                this.#getBuildCacheContextByOperation(consumer);
               if (consumerBuildCacheContext) {
                 consumerBuildCacheContext.isCacheWriteAllowed = false;
               }
@@ -575,21 +575,21 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
       );
 
       graph.hooks.afterExecuteIterationAsync.tap(PLUGIN_NAME, (status: OperationStatus) => {
-        this._buildCacheContextByOperation.clear();
+        this.#buildCacheContextByOperation.clear();
         return status;
       });
     });
   }
 
-  private _getBuildCacheContextByOperation(operation: Operation): IOperationBuildCacheContext | undefined {
+  #getBuildCacheContextByOperation(operation: Operation): IOperationBuildCacheContext | undefined {
     const buildCacheContext: IOperationBuildCacheContext | undefined =
-      this._buildCacheContextByOperation.get(operation);
+      this.#buildCacheContextByOperation.get(operation);
     return buildCacheContext;
   }
 
-  private _getBuildCacheContextByOperationOrThrow(operation: Operation): IOperationBuildCacheContext {
+  #getBuildCacheContextByOperationOrThrow(operation: Operation): IOperationBuildCacheContext {
     const buildCacheContext: IOperationBuildCacheContext | undefined =
-      this._getBuildCacheContextByOperation(operation);
+      this.#getBuildCacheContextByOperation(operation);
     if (!buildCacheContext) {
       // This should not happen
       throw new InternalError(`Build cache context for operation ${operation.name} should be defined`);
@@ -597,7 +597,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
     return buildCacheContext;
   }
 
-  private _tryGetOperationBuildCache(
+  #tryGetOperationBuildCache(
     options: ITryGetOperationBuildCacheOptions
   ): OperationBuildCache | undefined {
     const {
@@ -632,7 +632,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
   }
 
   // Get an OperationBuildCache only cache/restore log files
-  private async _tryGetLogOnlyOperationBuildCacheAsync(
+  async #tryGetLogOnlyOperationBuildCacheAsync(
     options: ITryGetLogOnlyOperationBuildCacheOptions
   ): Promise<OperationBuildCache | undefined> {
     const {
@@ -682,7 +682,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
     return operationBuildCache;
   }
 
-  private async _tryGetCobuildLockAsync({
+  async #tryGetCobuildLockAsync({
     cobuildConfiguration,
     buildCacheContext,
     operationBuildCache,
@@ -714,7 +714,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
     return buildCacheContext.cobuildLock;
   }
 
-  private async _createBuildCacheTerminalAsync({
+  async #createBuildCacheTerminalAsync({
     record,
     buildCacheContext,
     buildCacheEnabled,
@@ -741,7 +741,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
     // This creates the writer, only do this if necessary.
     const collatedWriter: CollatedWriter = record.collatedWriter;
     const cacheProjectLogWritable: TerminalWritable | undefined =
-      await this._tryGetBuildCacheTerminalWritableAsync({
+      await this.#tryGetBuildCacheTerminalWritableAsync({
         buildCacheContext,
         buildCacheEnabled,
         rushProject,
@@ -781,7 +781,7 @@ export class CacheableOperationPlugin implements IPhasedCommandPlugin {
     return new Terminal(buildCacheTerminalProvider);
   }
 
-  private async _tryGetBuildCacheTerminalWritableAsync({
+  async #tryGetBuildCacheTerminalWritableAsync({
     buildCacheEnabled,
     rushProject,
     buildCacheContext,
diff --git a/libraries/rush-lib/src/logic/operations/ConsoleTimelinePlugin.ts b/libraries/rush-lib/src/logic/operations/ConsoleTimelinePlugin.ts
index 770480762ce..09fd0efad5d 100644
--- a/libraries/rush-lib/src/logic/operations/ConsoleTimelinePlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/ConsoleTimelinePlugin.ts
@@ -44,10 +44,10 @@ BY PHASE:
  * Phased command plugin that emits a timeline to the console.
  */
 export class ConsoleTimelinePlugin implements IPhasedCommandPlugin {
-  private readonly _terminal: ITerminal;
+  readonly #terminal: ITerminal;
 
   public constructor(terminal: ITerminal) {
-    this._terminal = terminal;
+    this.#terminal = terminal;
   }
 
   public apply(hooks: PhasedCommandHooks): void {
@@ -59,7 +59,7 @@ export class ConsoleTimelinePlugin implements IPhasedCommandPlugin {
           operationResults: ReadonlyMap<Operation, IOperationExecutionResult>
         ): OperationStatus => {
           _printTimeline({
-            terminal: this._terminal,
+            terminal: this.#terminal,
             result: { status, operationResults },
             cobuildConfiguration: context.cobuildConfiguration
           });
diff --git a/libraries/rush-lib/src/logic/operations/DebugHashesPlugin.ts b/libraries/rush-lib/src/logic/operations/DebugHashesPlugin.ts
index 343f9b906ad..5c1391e65ed 100644
--- a/libraries/rush-lib/src/logic/operations/DebugHashesPlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/DebugHashesPlugin.ts
@@ -10,10 +10,10 @@ import type { IConfigurableOperation, IOperationStateHashComponents } from './IO
 const PLUGIN_NAME: 'DebugHashesPlugin' = 'DebugHashesPlugin';
 
 export class DebugHashesPlugin implements IPhasedCommandPlugin {
-  private readonly _terminal: ITerminal;
+  readonly #terminal: ITerminal;
 
   public constructor(terminal: ITerminal) {
-    this._terminal = terminal;
+    this.#terminal = terminal;
   }
 
   public apply(hooks: PhasedCommandHooks): void {
@@ -21,7 +21,7 @@ export class DebugHashesPlugin implements IPhasedCommandPlugin {
       graph.hooks.configureIteration.tap(
         PLUGIN_NAME,
         (operations: ReadonlyMap<Operation, IConfigurableOperation>) => {
-          const terminal: ITerminal = this._terminal;
+          const terminal: ITerminal = this.#terminal;
           terminal.writeLine(Colorize.blue(`===== Begin Hash Computation =====`));
           for (const [operation, record] of operations) {
             terminal.writeLine(Colorize.cyan(`--- ${operation.name} ---`));
diff --git a/libraries/rush-lib/src/logic/operations/IPCOperationRunner.ts b/libraries/rush-lib/src/logic/operations/IPCOperationRunner.ts
index f6545fee095..27249b26bfe 100644
--- a/libraries/rush-lib/src/logic/operations/IPCOperationRunner.ts
+++ b/libraries/rush-lib/src/logic/operations/IPCOperationRunner.ts
@@ -53,14 +53,14 @@ export class IPCOperationRunner implements IOperationRunner {
   public readonly silent: boolean = false;
   public readonly warningsAreAllowed: boolean;
 
-  private readonly _rushProject: RushConfigurationProject;
-  private readonly _initialCommand: string;
-  private readonly _incrementalCommand: string | undefined;
-  private readonly _commandForHash: string;
-  private readonly _ignoredParameterValues: ReadonlyArray<string>;
+  readonly #rushProject: RushConfigurationProject;
+  readonly #initialCommand: string;
+  readonly #incrementalCommand: string | undefined;
+  readonly #commandForHash: string;
+  readonly #ignoredParameterValues: ReadonlyArray<string>;
 
-  private _ipcProcess: ChildProcess | undefined;
-  private _processReadyPromise: Promise<void> | undefined;
+  #ipcProcess: ChildProcess | undefined;
+  #processReadyPromise: Promise<void> | undefined;
 
   public constructor(options: IIPCOperationRunnerOptions) {
     const {
@@ -75,16 +75,16 @@ export class IPCOperationRunner implements IOperationRunner {
     this.name = name;
     this.warningsAreAllowed =
       EnvironmentConfiguration.allowWarningsInSuccessfulBuild || allowWarningsOnSuccess;
-    this._rushProject = project;
-    this._initialCommand = initialCommand;
-    this._incrementalCommand = incrementalCommand;
-    this._commandForHash = commandForHash;
+    this.#rushProject = project;
+    this.#initialCommand = initialCommand;
+    this.#incrementalCommand = incrementalCommand;
+    this.#commandForHash = commandForHash;
 
-    this._ignoredParameterValues = ignoredParameterValues;
+    this.#ignoredParameterValues = ignoredParameterValues;
   }
 
   public get isActive(): boolean {
-    return !!(this._ipcProcess && !this._ipcProcess.killed && typeof this._ipcProcess.exitCode !== 'number');
+    return !!(this.#ipcProcess && !this.#ipcProcess.killed && typeof this.#ipcProcess.exitCode !== 'number');
   }
 
   public async executeAsync(
@@ -92,27 +92,27 @@ export class IPCOperationRunner implements IOperationRunner {
     lastState?: IOperationLastState
   ): Promise<OperationStatus> {
     const commandToRun: string =
-      lastState && this._incrementalCommand ? this._incrementalCommand : this._initialCommand;
+      lastState && this.#incrementalCommand ? this.#incrementalCommand : this.#initialCommand;
     const invalidate: (reason: string) => void = context.getInvalidateCallback();
     return await context.runWithTerminalAsync(
       async (terminal: ITerminal, terminalProvider: ITerminalProvider): Promise<OperationStatus> => {
         let isConnected: boolean = false;
-        if (!this._ipcProcess || typeof this._ipcProcess.exitCode === 'number') {
+        if (!this.#ipcProcess || typeof this.#ipcProcess.exitCode === 'number') {
           // Log any ignored parameters
-          if (this._ignoredParameterValues.length > 0) {
+          if (this.#ignoredParameterValues.length > 0) {
             terminal.writeLine(
-              `These parameters were ignored for this operation by project-level configuration: ${this._ignoredParameterValues.join(' ')}`
+              `These parameters were ignored for this operation by project-level configuration: ${this.#ignoredParameterValues.join(' ')}`
             );
           }
 
           // Run the operation
           terminal.writeLine('Invoking: ' + commandToRun);
 
-          const { rushConfiguration, projectFolder } = this._rushProject;
+          const { rushConfiguration, projectFolder } = this.#rushProject;
 
           const { environment: initialEnvironment } = context;
 
-          this._ipcProcess = Utilities.executeLifecycleCommandAsync(commandToRun, {
+          this.#ipcProcess = Utilities.executeLifecycleCommandAsync(commandToRun, {
             rushConfiguration,
             workingDirectory: projectFolder,
             initCwd: rushConfiguration.commonTempFolder,
@@ -127,11 +127,11 @@ export class IPCOperationRunner implements IOperationRunner {
 
           let resolveReadyPromise!: () => void;
 
-          this._processReadyPromise = new Promise<void>((resolve) => {
+          this.#processReadyPromise = new Promise<void>((resolve) => {
             resolveReadyPromise = resolve;
           });
 
-          this._ipcProcess.on('message', (message: unknown) => {
+          this.#ipcProcess.on('message', (message: unknown) => {
             if (isRequestRunEventMessage(message)) {
               const reason: string = message.detail
                 ? `${message.requestor}: ${message.detail}`
@@ -144,7 +144,7 @@ export class IPCOperationRunner implements IOperationRunner {
         } else {
           terminal.writeLine(`Connecting to existing IPC process...`);
         }
-        const subProcess: ChildProcess = this._ipcProcess;
+        const subProcess: ChildProcess = this.#ipcProcess;
         let hasWarningOrError: boolean = false;
 
         function onStdout(data: Buffer): void {
@@ -198,7 +198,7 @@ export class IPCOperationRunner implements IOperationRunner {
           subProcess.on('message', finishHandler);
           subProcess.on('error', reject);
           subProcess.on('exit', onExit);
-          this._processReadyPromise!.then(() => {
+          this.#processReadyPromise!.then(() => {
             isConnected = true;
             terminal.writeLine('Child supports IPC protocol. Sending "run" command...');
             const runCommand: IRunCommandMessage = {
@@ -225,11 +225,11 @@ export class IPCOperationRunner implements IOperationRunner {
   }
 
   public getConfigHash(): string {
-    return this._commandForHash;
+    return this.#commandForHash;
   }
 
   public async closeAsync(): Promise<void> {
-    const { _ipcProcess: subProcess } = this;
+    const subProcess: ChildProcess | undefined = this.#ipcProcess;
     if (!subProcess) {
       return;
     }
diff --git a/libraries/rush-lib/src/logic/operations/LegacySkipPlugin.ts b/libraries/rush-lib/src/logic/operations/LegacySkipPlugin.ts
index 846362409c5..03ebc73fbcc 100644
--- a/libraries/rush-lib/src/logic/operations/LegacySkipPlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/LegacySkipPlugin.ts
@@ -51,17 +51,17 @@ export interface ILegacySkipPluginOptions {
  * Core phased command plugin that implements the legacy skip detection logic, used when build cache is disabled.
  */
 export class LegacySkipPlugin implements IPhasedCommandPlugin {
-  private readonly _options: ILegacySkipPluginOptions;
+  readonly #options: ILegacySkipPluginOptions;
 
   public constructor(options: ILegacySkipPluginOptions) {
-    this._options = options;
+    this.#options = options;
   }
 
   public apply(hooks: PhasedCommandHooks): void {
     const stateMap: WeakMap<Operation, ILegacySkipRecord> = new WeakMap();
 
     const { terminal, changedProjectsOnly, isIncrementalBuildAllowed, allowWarningsInSuccessfulBuild } =
-      this._options;
+      this.#options;
 
     hooks.onGraphCreatedAsync.tap(PLUGIN_NAME, (graph) => {
       graph.hooks.beforeExecuteIterationAsync.tap(
diff --git a/libraries/rush-lib/src/logic/operations/NodeDiagnosticDirPlugin.ts b/libraries/rush-lib/src/logic/operations/NodeDiagnosticDirPlugin.ts
index 70e1d88c69f..ee3ae0b8c76 100644
--- a/libraries/rush-lib/src/logic/operations/NodeDiagnosticDirPlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/NodeDiagnosticDirPlugin.ts
@@ -20,10 +20,10 @@ export interface INodeDiagnosticDirPluginOptions {
  * Phased command plugin that configures the NodeJS --diagnostic-dir option to contain the project and phase name.
  */
 export class NodeDiagnosticDirPlugin implements IPhasedCommandPlugin {
-  private readonly _diagnosticsDir: string;
+  readonly #diagnosticsDir: string;
 
   public constructor(options: INodeDiagnosticDirPluginOptions) {
-    this._diagnosticsDir = options.diagnosticDir;
+    this.#diagnosticsDir = options.diagnosticDir;
   }
 
   public apply(hooks: PhasedCommandHooks): void {
@@ -31,7 +31,7 @@ export class NodeDiagnosticDirPlugin implements IPhasedCommandPlugin {
       const { associatedProject } = operation;
 
       const diagnosticDir: string = path.resolve(
-        this._diagnosticsDir,
+        this.#diagnosticsDir,
         associatedProject.packageName,
         operation.logFilenameIdentifier
       );
diff --git a/libraries/rush-lib/src/logic/operations/OperationChunkTap.ts b/libraries/rush-lib/src/logic/operations/OperationChunkTap.ts
index 89d434df150..ac26c035f1d 100644
--- a/libraries/rush-lib/src/logic/operations/OperationChunkTap.ts
+++ b/libraries/rush-lib/src/logic/operations/OperationChunkTap.ts
@@ -12,20 +12,20 @@ import { TerminalWritable, type ITerminalChunk } from '@rushstack/terminal';
  * @internal
  */
 export class OperationChunkTap extends TerminalWritable {
-  private readonly _operationId: string;
-  private readonly _onChunk: (operationId: string, chunk: ITerminalChunk) => void;
+  readonly #operationId: string;
+  readonly #onChunk: (operationId: string, chunk: ITerminalChunk) => void;
 
   public constructor(
     operationId: string,
     onChunk: (operationId: string, chunk: ITerminalChunk) => void
   ) {
     super({ preventAutoclose: true });
-    this._operationId = operationId;
-    this._onChunk = onChunk;
+    this.#operationId = operationId;
+    this.#onChunk = onChunk;
   }
 
   /** {@inheritDoc @rushstack/terminal#TerminalWritable.onWriteChunk} */
   public onWriteChunk(chunk: ITerminalChunk): void {
-    this._onChunk(this._operationId, chunk);
+    this.#onChunk(this.#operationId, chunk);
   }
 }
diff --git a/libraries/rush-lib/src/logic/operations/OperationExecutionRecord.ts b/libraries/rush-lib/src/logic/operations/OperationExecutionRecord.ts
index 47317ecfac8..7ce773d0165 100644
--- a/libraries/rush-lib/src/logic/operations/OperationExecutionRecord.ts
+++ b/libraries/rush-lib/src/logic/operations/OperationExecutionRecord.ts
@@ -167,12 +167,12 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
 
   public logFilePaths: ILogFilePaths | undefined;
 
-  private readonly _context: IOperationExecutionRecordContext;
+  readonly #context: IOperationExecutionRecordContext;
 
-  private _collatedWriter: CollatedWriter | undefined = undefined;
-  private _status: OperationStatus;
-  private _stateHash: string | undefined;
-  private _stateHashComponents: IOperationStateHashComponents | undefined;
+  #collatedWriter: CollatedWriter | undefined = undefined;
+  #status: OperationStatus;
+  #stateHash: string | undefined;
+  #stateHashComponents: IOperationStateHashComponents | undefined;
 
   public constructor(operation: Operation, context: IOperationExecutionRecordContext) {
     const { runner, associatedPhase, associatedProject, enabled } = operation;
@@ -195,10 +195,10 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
       operation
     });
 
-    this._context = context;
-    this._status = operation.dependencies.size > 0 ? OperationStatus.Waiting : OperationStatus.Ready;
-    this._stateHash = undefined;
-    this._stateHashComponents = undefined;
+    this.#context = context;
+    this.#status = operation.dependencies.size > 0 ? OperationStatus.Waiting : OperationStatus.Ready;
+    this.#stateHash = undefined;
+    this.#stateHashComponents = undefined;
   }
 
   public get name(): string {
@@ -206,19 +206,19 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
   }
 
   public get debugMode(): boolean {
-    return this._context.debugMode;
+    return this.#context.debugMode;
   }
 
   public get quietMode(): boolean {
-    return this._context.quietMode;
+    return this.#context.quietMode;
   }
 
   public get collatedWriter(): CollatedWriter {
     // Lazy instantiate because the registerTask() call affects display ordering
-    if (!this._collatedWriter) {
-      this._collatedWriter = this._context.streamCollator.registerTask(this.name);
+    if (!this.#collatedWriter) {
+      this.#collatedWriter = this.#context.streamCollator.registerTask(this.name);
     }
-    return this._collatedWriter;
+    return this.#collatedWriter;
   }
 
   public get nonCachedDurationMs(): number | undefined {
@@ -232,12 +232,12 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
   }
 
   public get environment(): IEnvironment | undefined {
-    return this._context.createEnvironment?.(this);
+    return this.#context.createEnvironment?.(this);
   }
 
   public getInvalidateCallback(): (reason: string) => void {
     const invalidateFn: ((operations: Iterable<Operation>, reason: string) => void) | undefined =
-      this._context.invalidate;
+      this.#context.invalidate;
     const operations: [Operation] = [this.operation];
     return (reason: string) => {
       invalidateFn?.(operations, reason);
@@ -259,16 +259,16 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
    * 'failure'.
    */
   public get status(): OperationStatus {
-    return this._status;
+    return this.#status;
   }
   public set status(newStatus: OperationStatus) {
-    if (newStatus === this._status) {
+    if (newStatus === this.#status) {
       return;
     }
-    const previousStatus: OperationStatus = this._status;
-    this._status = newStatus;
-    this._context.eventSink?.onOperationStatusChanged?.(this, previousStatus);
-    this._context.onOperationStateChanged?.(this);
+    const previousStatus: OperationStatus = this.#status;
+    this.#status = newStatus;
+    this.#context.eventSink?.onOperationStatusChanged?.(this, previousStatus);
+    this.#context.onOperationStateChanged?.(this);
   }
 
   /**
@@ -276,7 +276,7 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
    * @internal
    */
   public get eventSink(): IOperationGraphEventSink | undefined {
-    return this._context.eventSink;
+    return this.#context.eventSink;
   }
 
   public get silent(): boolean {
@@ -284,7 +284,7 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
   }
 
   public getStateHash(): string {
-    if (this._stateHash === undefined) {
+    if (this.#stateHash === undefined) {
       const { dependencies, local, config } = this.getStateHashComponents();
 
       const hasher: crypto.Hash = crypto.createHash('sha1');
@@ -295,14 +295,14 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
       hasher.update(`${RushConstants.hashDelimiter}config=${config}`);
 
       const hash: string = hasher.digest('hex');
-      this._stateHash = hash;
+      this.#stateHash = hash;
     }
-    return this._stateHash;
+    return this.#stateHash;
   }
 
   public getStateHashComponents(): IOperationStateHashComponents {
-    if (!this._stateHashComponents) {
-      const { inputsSnapshot } = this._context;
+    if (!this.#stateHashComponents) {
+      const { inputsSnapshot } = this.#context;
 
       if (!inputsSnapshot) {
         throw new Error(`Cannot calculate state hash without git.`);
@@ -332,9 +332,9 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
       // - CLI parameters (ShellOperationRunner)
       const config: string = this.runner.getConfigHash();
 
-      this._stateHashComponents = { dependencies, local, config };
+      this.#stateHashComponents = { dependencies, local, config };
     }
-    return this._stateHashComponents;
+    return this.#stateHashComponents;
   }
 
   /**
@@ -366,7 +366,7 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
     if (logFilePaths) {
       // Only assign if it won't clear an existing value; stopgap until we support multiple sets of log files per operation.
       this.logFilePaths = logFilePaths;
-      this._context.onOperationStateChanged?.(this);
+      this.#context.onOperationStateChanged?.(this);
     }
 
     try {
@@ -397,7 +397,7 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
       });
 
       const chunkTapDestinations: TerminalWritable[] = [];
-      const eventSink: IOperationGraphEventSink | undefined = this._context.eventSink;
+      const eventSink: IOperationGraphEventSink | undefined = this.#context.eventSink;
       if (eventSink?.onOperationChunk) {
         // Tap the stream upstream of the quiet-mode discard so the sink observes
         // the exact bytes the collated writer would receive, regardless of verbosity.
@@ -485,9 +485,9 @@ export class OperationExecutionRecord implements IOperationRunnerContext, IOpera
       await executeContext.onResultAsync(this);
     } finally {
       if (this.isTerminal) {
-        this._collatedWriter?.close();
-        if (this._collatedWriter) {
-          this._context.eventSink?.onOperationStreamClosed?.(this.name);
+        this.#collatedWriter?.close();
+        if (this.#collatedWriter) {
+          this.#context.eventSink?.onOperationStreamClosed?.(this.name);
         }
         this.stdioSummarizer.close();
         this.problemCollector.close();
diff --git a/libraries/rush-lib/src/logic/operations/OperationGraph.ts b/libraries/rush-lib/src/logic/operations/OperationGraph.ts
index 58e6c692aad..7cd67d15d37 100644
--- a/libraries/rush-lib/src/logic/operations/OperationGraph.ts
+++ b/libraries/rush-lib/src/logic/operations/OperationGraph.ts
@@ -160,22 +160,22 @@ export class OperationGraph implements IOperationGraph {
   public readonly hooks: OperationGraphHooks = new OperationGraphHooks();
   public readonly operations: Set<Operation>;
   public readonly abortController: AbortController;
-  private readonly _sortedOperations: readonly Operation[];
+  readonly #sortedOperations: readonly Operation[];
 
   public resultByOperation: Map<Operation, OperationExecutionRecord>;
 
   // Mutable properties extracted from options
-  private _parallelism: number;
-  private _maxParallelism: number;
-  private _debugMode: boolean;
-  private _quietMode: boolean;
-  private _allowOversubscription: boolean;
-  private _pauseNextIteration: boolean;
+  #parallelism: number;
+  #maxParallelism: number;
+  #debugMode: boolean;
+  #quietMode: boolean;
+  #allowOversubscription: boolean;
+  #pauseNextIteration: boolean;
 
   // Immutable properties from options
-  private readonly _isWatch: boolean;
-  private readonly _telemetry: IOperationGraphTelemetry | undefined;
-  private readonly _getInputsSnapshotAsync: (() => Promise<IInputsSnapshot | undefined>) | undefined;
+  readonly #isWatch: boolean;
+  readonly #telemetry: IOperationGraphTelemetry | undefined;
+  readonly #getInputsSnapshotAsync: (() => Promise<IInputsSnapshot | undefined>) | undefined;
 
   /**
    * Records invalidated during the current iteration that could not be marked `Ready` immediately
@@ -183,12 +183,12 @@ export class OperationGraph implements IOperationGraph {
    * `records` map (mutating it mid-iteration would corrupt the summarizer's view of results).
    * Maps each record to the invalidation reason; applied once the iteration completes.
    */
-  private readonly _deferredInvalidations: Map<OperationExecutionRecord, string | undefined> = new Map();
+  readonly #deferredInvalidations: Map<OperationExecutionRecord, string | undefined> = new Map();
 
-  private _currentIteration: IExecutionIterationContext | undefined = undefined;
-  private _scheduledIteration: IExecutionIterationContext | undefined = undefined;
+  #currentIteration: IExecutionIterationContext | undefined = undefined;
+  #scheduledIteration: IExecutionIterationContext | undefined = undefined;
 
-  private _terminalSplitter: SplitterTransform;
+  #terminalSplitter: SplitterTransform;
 
   /**
    * Optional structured event sink enabling "dual-emit": every operation state
@@ -201,10 +201,10 @@ export class OperationGraph implements IOperationGraph {
    */
   public eventSink: IOperationGraphEventSink | undefined = undefined;
 
-  private _idleTimeout: NodeJS.Timeout | undefined = undefined;
+  #idleTimeout: NodeJS.Timeout | undefined = undefined;
   /** Tracks if a graph state change notification has been scheduled for next tick. */
-  private _graphStateChangeScheduled: boolean = false;
-  private _status: OperationStatus = OperationStatus.Ready;
+  #graphStateChangeScheduled: boolean = false;
+  #status: OperationStatus = OperationStatus.Ready;
 
   public constructor(operations: Set<Operation>, options: IOperationGraphOptions) {
     const {
@@ -223,26 +223,26 @@ export class OperationGraph implements IOperationGraph {
 
     this.operations = operations;
 
-    this._maxParallelism = maxParallelism;
-    this._parallelism = coerceParallelism(parallelism, maxParallelism, 1);
-    this._debugMode = debugMode;
-    this._quietMode = quietMode;
-    this._allowOversubscription = allowOversubscription;
-    this._pauseNextIteration = pauseNextIteration;
-    this._isWatch = isWatch;
-    this._telemetry = telemetry;
-    this._getInputsSnapshotAsync = getInputsSnapshotAsync;
-
-    this._sortedOperations = Array.from(operations).sort(sortOperationsByName);
-    this._terminalSplitter = new SplitterTransform({ destinations });
+    this.#maxParallelism = maxParallelism;
+    this.#parallelism = coerceParallelism(parallelism, maxParallelism, 1);
+    this.#debugMode = debugMode;
+    this.#quietMode = quietMode;
+    this.#allowOversubscription = allowOversubscription;
+    this.#pauseNextIteration = pauseNextIteration;
+    this.#isWatch = isWatch;
+    this.#telemetry = telemetry;
+    this.#getInputsSnapshotAsync = getInputsSnapshotAsync;
+
+    this.#sortedOperations = Array.from(operations).sort(sortOperationsByName);
+    this.#terminalSplitter = new SplitterTransform({ destinations });
     this.resultByOperation = new Map();
     this.abortController = abortController;
 
     this.abortController.signal.addEventListener(
       'abort',
       () => {
-        if (this._idleTimeout) {
-          clearTimeout(this._idleTimeout);
+        if (this.#idleTimeout) {
+          clearTimeout(this.#idleTimeout);
         }
         void this.closeRunnersAsync();
       },
@@ -341,89 +341,89 @@ export class OperationGraph implements IOperationGraph {
   }
 
   public get parallelism(): number {
-    return this._parallelism;
+    return this.#parallelism;
   }
   public set parallelism(value: Parallelism) {
-    const coerced: number = coerceParallelism(value, this._maxParallelism, 1);
-    if (coerced !== this._parallelism) {
-      this._parallelism = coerced;
-      this._scheduleManagerStateChanged();
+    const coerced: number = coerceParallelism(value, this.#maxParallelism, 1);
+    if (coerced !== this.#parallelism) {
+      this.#parallelism = coerced;
+      this.#scheduleManagerStateChanged();
     }
   }
 
   public get debugMode(): boolean {
-    return this._debugMode;
+    return this.#debugMode;
   }
   public set debugMode(value: boolean) {
-    if (value !== this._debugMode) {
-      this._debugMode = value;
-      this._scheduleManagerStateChanged();
+    if (value !== this.#debugMode) {
+      this.#debugMode = value;
+      this.#scheduleManagerStateChanged();
     }
   }
 
   public get quietMode(): boolean {
-    return this._quietMode;
+    return this.#quietMode;
   }
   public set quietMode(value: boolean) {
-    if (value !== this._quietMode) {
-      this._quietMode = value;
-      this._scheduleManagerStateChanged();
+    if (value !== this.#quietMode) {
+      this.#quietMode = value;
+      this.#scheduleManagerStateChanged();
     }
   }
 
   public get allowOversubscription(): boolean {
-    return this._allowOversubscription;
+    return this.#allowOversubscription;
   }
   public set allowOversubscription(value: boolean) {
-    if (value !== this._allowOversubscription) {
-      this._allowOversubscription = value;
-      this._scheduleManagerStateChanged();
+    if (value !== this.#allowOversubscription) {
+      this.#allowOversubscription = value;
+      this.#scheduleManagerStateChanged();
     }
   }
 
   public get pauseNextIteration(): boolean {
-    return this._pauseNextIteration;
+    return this.#pauseNextIteration;
   }
   public set pauseNextIteration(value: boolean) {
-    if (value !== this._pauseNextIteration) {
-      this._pauseNextIteration = value;
-      this._scheduleManagerStateChanged();
+    if (value !== this.#pauseNextIteration) {
+      this.#pauseNextIteration = value;
+      this.#scheduleManagerStateChanged();
 
-      this._setIdleTimeout();
+      this.#setIdleTimeout();
     }
   }
 
   public get hasScheduledIteration(): boolean {
-    return !!this._scheduledIteration;
+    return !!this.#scheduledIteration;
   }
 
   public get status(): OperationStatus {
-    return this._status;
+    return this.#status;
   }
 
   public get terminalDestinations(): ReadonlySet<TerminalWritable> {
-    return this._terminalSplitter.destinations;
+    return this.#terminalSplitter.destinations;
   }
 
-  private _setStatus(newStatus: OperationStatus): void {
-    if (this._status !== newStatus) {
-      this._status = newStatus;
-      this._scheduleManagerStateChanged();
+  #setStatus(newStatus: OperationStatus): void {
+    if (this.#status !== newStatus) {
+      this.#status = newStatus;
+      this.#scheduleManagerStateChanged();
     }
   }
 
-  private _setScheduledIteration(iteration: IExecutionIterationContext | undefined): void {
-    const hadScheduled: boolean = !!this._scheduledIteration;
-    this._scheduledIteration = iteration;
-    if (hadScheduled !== !!this._scheduledIteration) {
-      this._scheduleManagerStateChanged();
+  #setScheduledIteration(iteration: IExecutionIterationContext | undefined): void {
+    const hadScheduled: boolean = !!this.#scheduledIteration;
+    this.#scheduledIteration = iteration;
+    if (hadScheduled !== !!this.#scheduledIteration) {
+      this.#scheduleManagerStateChanged();
     }
   }
 
   public async closeRunnersAsync(operations?: Iterable<Operation>): Promise<void> {
     const runnersToClose: IOperationRunnerCloseEntry[] = [];
     const recordMap: ReadonlyMap<Operation, OperationExecutionRecord> =
-      this._currentIteration?.records ?? this.resultByOperation;
+      this.#currentIteration?.records ?? this.resultByOperation;
     const closedRecords: Set<OperationExecutionRecord> = new Set();
     for (const operation of operations ?? this.operations) {
       const closeAsync: (() => Promise<void>) | undefined = operation.runner?.closeAsync;
@@ -459,7 +459,7 @@ export class OperationGraph implements IOperationGraph {
 
   public invalidateOperations(operations?: Iterable<Operation>, reason?: string): void {
     const invalidated: Set<Operation> = new Set();
-    const currentIteration: IExecutionIterationContext | undefined = this._currentIteration;
+    const currentIteration: IExecutionIterationContext | undefined = this.#currentIteration;
     const currentIterationRecords: Map<Operation, OperationExecutionRecord> | undefined =
       currentIteration?.records;
     for (const operation of operations ?? this.operations) {
@@ -470,7 +470,7 @@ export class OperationGraph implements IOperationGraph {
           // resultByOperation. Mutating its status now would corrupt the iteration's result
           // snapshot (used by the summarizer). Defer the reset until the iteration ends, and
           // abort so the operation can be re-run in the next iteration.
-          this._deferredInvalidations.set(existing, reason);
+          this.#deferredInvalidations.set(existing, reason);
           currentIteration?.abortController.abort();
         } else {
           existing.status = OperationStatus.Ready;
@@ -482,7 +482,7 @@ export class OperationGraph implements IOperationGraph {
       this.hooks.onInvalidateOperations.call(invalidated, reason);
     }
     if (!currentIteration) {
-      this._setStatus(OperationStatus.Ready);
+      this.#setStatus(OperationStatus.Ready);
     }
   }
 
@@ -495,7 +495,7 @@ export class OperationGraph implements IOperationGraph {
   public async executeAsync(iterationOptions: IOperationGraphIterationOptions): Promise<IExecutionResult> {
     await this.abortCurrentIterationAsync();
     const scheduled: IExecutionIterationContext | undefined =
-      await this._scheduleIterationAsync(iterationOptions);
+      await this.#scheduleIterationAsync(iterationOptions);
     if (!scheduled) {
       return {
         operationResults: this.resultByOperation,
@@ -515,7 +515,7 @@ export class OperationGraph implements IOperationGraph {
    * @returns A promise that resolves to true if the iteration was successfully queued, or false if it was not.
    */
   public async scheduleIterationAsync(iterationOptions: IOperationGraphIterationOptions): Promise<boolean> {
-    return !!(await this._scheduleIterationAsync(iterationOptions));
+    return !!(await this.#scheduleIterationAsync(iterationOptions));
   }
 
   /**
@@ -525,23 +525,23 @@ export class OperationGraph implements IOperationGraph {
   public async executeScheduledIterationAsync(): Promise<boolean> {
     await this.abortCurrentIterationAsync();
 
-    const iteration: IExecutionIterationContext | undefined = this._scheduledIteration;
+    const iteration: IExecutionIterationContext | undefined = this.#scheduledIteration;
 
     if (!iteration) {
       return false;
     }
 
-    this._currentIteration = iteration;
-    this._setScheduledIteration(undefined);
+    this.#currentIteration = iteration;
+    this.#setScheduledIteration(undefined);
 
-    iteration.promise = this._executeInnerAsync(this._currentIteration).finally(() => {
-      this._currentIteration = undefined;
+    iteration.promise = this.#executeInnerAsync(this.#currentIteration).finally(() => {
+      this.#currentIteration = undefined;
 
       // Apply any status resets that were deferred because the records were part of the
       // now-completed iteration and could not be mutated mid-iteration.
       // Coalesce by reason so consumers receive one notification per reason group.
       const byReason: Map<string | undefined, Operation[]> = new Map();
-      for (const [record, deferredReason] of this._deferredInvalidations) {
+      for (const [record, deferredReason] of this.#deferredInvalidations) {
         record.status = OperationStatus.Ready;
         let group: Operation[] | undefined = byReason.get(deferredReason);
         if (!group) {
@@ -550,12 +550,12 @@ export class OperationGraph implements IOperationGraph {
         }
         group.push(record.operation);
       }
-      this._deferredInvalidations.clear();
+      this.#deferredInvalidations.clear();
       for (const [deferredReason, ops] of byReason) {
         this.hooks.onInvalidateOperations.call(ops, deferredReason);
       }
 
-      this._setIdleTimeout();
+      this.#setIdleTimeout();
     });
 
     await iteration.promise;
@@ -563,7 +563,7 @@ export class OperationGraph implements IOperationGraph {
   }
 
   public async abortCurrentIterationAsync(): Promise<void> {
-    const iteration: IExecutionIterationContext | undefined = this._currentIteration;
+    const iteration: IExecutionIterationContext | undefined = this.#currentIteration;
     if (iteration) {
       iteration.abortController.abort();
       try {
@@ -573,44 +573,45 @@ export class OperationGraph implements IOperationGraph {
       }
     }
 
-    this._setIdleTimeout();
+    this.#setIdleTimeout();
   }
 
   public addTerminalDestination(destination: TerminalWritable): void {
-    this._terminalSplitter.addDestination(destination);
+    this.#terminalSplitter.addDestination(destination);
   }
 
   public removeTerminalDestination(destination: TerminalWritable, close: boolean = true): boolean {
-    return this._terminalSplitter.removeDestination(destination, close);
+    return this.#terminalSplitter.removeDestination(destination, close);
   }
 
-  private _setIdleTimeout(): void {
-    if (this._currentIteration || this.abortController.signal.aborted) {
+  #setIdleTimeout(): void {
+    if (this.#currentIteration || this.abortController.signal.aborted) {
       return;
     }
 
-    if (!this._idleTimeout) {
-      this._idleTimeout = setTimeout(this._onIdle, 0);
+    if (!this.#idleTimeout) {
+      this.#idleTimeout = setTimeout(this.#onIdle, 0);
     }
   }
 
-  private _onIdle = (): void => {
-    this._idleTimeout = undefined;
-    if (this._currentIteration || this.abortController.signal.aborted) {
+  #onIdle = (): void => {
+    this.#idleTimeout = undefined;
+    if (this.#currentIteration || this.abortController.signal.aborted) {
       return;
     }
 
-    if (!this.pauseNextIteration && this._scheduledIteration) {
+    if (!this.pauseNextIteration && this.#scheduledIteration) {
       void this.executeScheduledIterationAsync();
     } else {
       this.hooks.onIdle.call();
     }
   };
 
-  private async _scheduleIterationAsync(
+  async #scheduleIterationAsync(
     iterationOptions: IOperationGraphIterationOptions
   ): Promise<IExecutionIterationContext | undefined> {
-    const { _getInputsSnapshotAsync: getInputsSnapshotAsync } = this;
+    const getInputsSnapshotAsync: (() => Promise<IInputsSnapshot | undefined>) | undefined =
+      this.#getInputsSnapshotAsync;
 
     const { startTime = performance.now(), inputsSnapshot = await getInputsSnapshotAsync?.() } =
       iterationOptions;
@@ -625,7 +626,7 @@ export class OperationGraph implements IOperationGraph {
     // streamCollator --> colorsNewlinesTransform --> StdioWritable
     //
     const colorsNewlinesTransform: TextRewriterTransform = new TextRewriterTransform({
-      destination: this._terminalSplitter,
+      destination: this.#terminalSplitter,
       normalizeNewlines: NewlineKind.OsDefault,
       removeColors: !ConsoleTerminalProvider.supportsColor
     });
@@ -635,7 +636,7 @@ export class OperationGraph implements IOperationGraph {
       onWriterActive
     });
 
-    const sortedOperations: readonly Operation[] = this._sortedOperations;
+    const sortedOperations: readonly Operation[] = this.#sortedOperations;
 
     const graph: OperationGraph = this;
 
@@ -650,7 +651,7 @@ export class OperationGraph implements IOperationGraph {
       streamCollator,
       terminal,
       inputsSnapshot,
-      maxParallelism: this._maxParallelism,
+      maxParallelism: this.#maxParallelism,
       onOperationStateChanged: undefined,
       createEnvironment: createEnvironmentForOperation,
       invalidate: (operations: Iterable<Operation>, reason: string) => {
@@ -717,7 +718,7 @@ export class OperationGraph implements IOperationGraph {
       return;
     }
 
-    this._setScheduledIteration(iterationContext);
+    this.#setScheduledIteration(iterationContext);
     // Notify listeners that an iteration has been scheduled with the planned operation records
     try {
       this.hooks.onIterationScheduled.call(iterationContext.records);
@@ -728,8 +729,8 @@ export class OperationGraph implements IOperationGraph {
       terminal.writeStderrLine(Colorize.red(errorMessage));
       throw e;
     }
-    if (!this._currentIteration) {
-      this._setIdleTimeout();
+    if (!this.#currentIteration) {
+      this.#setIdleTimeout();
     } else if (!this.pauseNextIteration) {
       void this.abortCurrentIterationAsync();
     }
@@ -779,13 +780,13 @@ export class OperationGraph implements IOperationGraph {
    * only trigger the hook once. This avoids redundant re-computation in listeners (e.g. UI refresh) while preserving
    * ordering guarantees that the notification occurs after the initiating state changes are fully applied.
    */
-  private _scheduleManagerStateChanged(): void {
-    if (this._graphStateChangeScheduled || this.abortController.signal.aborted) {
+  #scheduleManagerStateChanged(): void {
+    if (this.#graphStateChangeScheduled || this.abortController.signal.aborted) {
       return;
     }
-    this._graphStateChangeScheduled = true;
+    this.#graphStateChangeScheduled = true;
     process.nextTick(() => {
-      this._graphStateChangeScheduled = false;
+      this.#graphStateChangeScheduled = false;
       this.hooks.onGraphStateChanged.call(this);
     });
   }
@@ -794,8 +795,8 @@ export class OperationGraph implements IOperationGraph {
    * Executes all operations which have been registered, returning a promise which is resolved when all operations have been processed to a final state.
    * The abortController can be used to cancel the execution of any operations that have not yet begun execution.
    */
-  private async _executeInnerAsync(iterationContext: IExecutionIterationContext): Promise<OperationStatus> {
-    this._setStatus(OperationStatus.Executing);
+  async #executeInnerAsync(iterationContext: IExecutionIterationContext): Promise<OperationStatus> {
+    this.#setStatus(OperationStatus.Executing);
 
     const { hooks } = this;
 
@@ -974,16 +975,16 @@ export class OperationGraph implements IOperationGraph {
       return OperationStatus.Success;
     })();
 
-    this._setStatus(
+    this.#setStatus(
       (await measureAsyncFn(`${PERF_PREFIX}:afterExecuteIterationAsync`, async () => {
         return await hooks.afterExecuteIterationAsync.promise(status, executionRecords, iterationOptions);
       })) ?? status
     );
 
-    const { _telemetry: telemetry } = this;
+    const telemetry: IOperationGraphTelemetry | undefined = this.#telemetry;
     if (telemetry) {
       const logEntry: ITelemetryData = measureFn(`${PERF_PREFIX}:prepareTelemetry`, () => {
-        const isWatch: boolean = this._isWatch;
+        const isWatch: boolean = this.#isWatch;
         const jsonOperationResults: Record<string, ITelemetryOperationResult> = {};
 
         const durationInSeconds: number = (performance.now() - (iterationContext.startTime ?? 0)) / 1000;
diff --git a/libraries/rush-lib/src/logic/operations/OperationMetadataManager.ts b/libraries/rush-lib/src/logic/operations/OperationMetadataManager.ts
index e3f1f2f0dc5..51007b65a60 100644
--- a/libraries/rush-lib/src/logic/operations/OperationMetadataManager.ts
+++ b/libraries/rush-lib/src/logic/operations/OperationMetadataManager.ts
@@ -49,10 +49,10 @@ export interface ILogChunkStorage {
 export class OperationMetadataManager {
   public readonly stateFile: OperationStateFile;
   public readonly logFilenameIdentifier: string;
-  private readonly _metadataFolderPath: string;
-  private readonly _logPath: string;
-  private readonly _errorLogPath: string;
-  private readonly _logChunksPath: string;
+  readonly #metadataFolderPath: string;
+  readonly #logPath: string;
+  readonly #errorLogPath: string;
+  readonly #logChunksPath: string;
   public wasCobuilt: boolean = false;
 
   public constructor(options: IOperationMetadataManagerOptions) {
@@ -70,10 +70,10 @@ export class OperationMetadataManager {
       metadataFolder: metadataFolderPath
     });
 
-    this._metadataFolderPath = metadataFolderPath;
-    this._logPath = `${projectFolder}/${metadataFolderPath}/all.log`;
-    this._errorLogPath = `${projectFolder}/${metadataFolderPath}/error.log`;
-    this._logChunksPath = `${projectFolder}/${metadataFolderPath}/log-chunks.jsonl`;
+    this.#metadataFolderPath = metadataFolderPath;
+    this.#logPath = `${projectFolder}/${metadataFolderPath}/all.log`;
+    this.#errorLogPath = `${projectFolder}/${metadataFolderPath}/error.log`;
+    this.#logChunksPath = `${projectFolder}/${metadataFolderPath}/log-chunks.jsonl`;
   }
 
   /**
@@ -84,7 +84,7 @@ export class OperationMetadataManager {
    * Example: `.rush/temp/operation/_phase_build/error.log`
    */
   public get metadataFolderPath(): string {
-    return this._metadataFolderPath;
+    return this.#metadataFolderPath;
   }
 
   public async saveAsync({
@@ -105,15 +105,15 @@ export class OperationMetadataManager {
     const copyFileOptions: IFileSystemCopyFileOptions[] = [
       {
         sourcePath: logPath,
-        destinationPath: this._logPath
+        destinationPath: this.#logPath
       },
       {
         sourcePath: errorLogPath,
-        destinationPath: this._errorLogPath
+        destinationPath: this.#errorLogPath
       },
       {
         sourcePath: logChunksPath,
-        destinationPath: this._logChunksPath
+        destinationPath: this.#logChunksPath
       }
     ];
 
@@ -150,7 +150,7 @@ export class OperationMetadataManager {
       this.stateFile.state?.cobuildRunnerId !== cobuildRunnerId;
 
     try {
-      const rawLogChunks: string = await FileSystem.readFileAsync(this._logChunksPath);
+      const rawLogChunks: string = await FileSystem.readFileAsync(this.#logChunksPath);
       const chunks: ITerminalChunk[] = [];
       for (const chunk of rawLogChunks.split('\n')) {
         if (chunk) {
@@ -167,7 +167,7 @@ export class OperationMetadataManager {
     } catch (e) {
       if (FileSystem.isNotExistError(e)) {
         // Log chunks file doesn't exist, try to restore log file
-        await restoreFromLogFile(terminal, this._logPath);
+        await restoreFromLogFile(terminal, this.#logPath);
       } else {
         throw e;
       }
@@ -176,7 +176,7 @@ export class OperationMetadataManager {
     // Try to restore cached error log as error log file
     try {
       await FileSystem.copyFileAsync({
-        sourcePath: this._errorLogPath,
+        sourcePath: this.#errorLogPath,
         destinationPath: errorLogPath
       });
     } catch (e) {
diff --git a/libraries/rush-lib/src/logic/operations/OperationResultSummarizerPlugin.ts b/libraries/rush-lib/src/logic/operations/OperationResultSummarizerPlugin.ts
index 1ff82c3baf6..7f9c171a119 100644
--- a/libraries/rush-lib/src/logic/operations/OperationResultSummarizerPlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/OperationResultSummarizerPlugin.ts
@@ -25,10 +25,10 @@ type IOperationsByStatus = Map<OperationStatus, IOperationAndResult[]>;
  * Phased command plugin that emits a summary of build results to the console.
  */
 export class OperationResultSummarizerPlugin implements IPhasedCommandPlugin {
-  private readonly _terminal: ITerminal;
+  readonly #terminal: ITerminal;
 
   public constructor(terminal: ITerminal) {
-    this._terminal = terminal;
+    this.#terminal = terminal;
   }
 
   public apply(hooks: PhasedCommandHooks): void {
@@ -40,7 +40,7 @@ export class OperationResultSummarizerPlugin implements IPhasedCommandPlugin {
           status: OperationStatus,
           results: ReadonlyMap<Operation, IOperationExecutionResult>
         ): OperationStatus => {
-          _printOperationStatus(this._terminal, { status, operationResults: results });
+          _printOperationStatus(this.#terminal, { status, operationResults: results });
           return status;
         }
       );
diff --git a/libraries/rush-lib/src/logic/operations/OperationStateFile.ts b/libraries/rush-lib/src/logic/operations/OperationStateFile.ts
index b05cf70b57f..c0773f066ed 100644
--- a/libraries/rush-lib/src/logic/operations/OperationStateFile.ts
+++ b/libraries/rush-lib/src/logic/operations/OperationStateFile.ts
@@ -26,7 +26,7 @@ export interface IOperationStateJson {
  * @internal
  */
 export class OperationStateFile {
-  private _state: IOperationStateJson | undefined;
+  #state: IOperationStateJson | undefined;
 
   /**
    * The path of the state json file.
@@ -51,25 +51,25 @@ export class OperationStateFile {
   }
 
   public get state(): IOperationStateJson | undefined {
-    return this._state;
+    return this.#state;
   }
 
   public async writeAsync(json: IOperationStateJson): Promise<void> {
     await JsonFile.saveAsync(json, this.filepath, { ensureFolderExists: true, ignoreUndefinedValues: true });
-    this._state = json;
+    this.#state = json;
   }
 
   public async tryRestoreAsync(): Promise<IOperationStateJson | undefined> {
     try {
-      this._state = await JsonFile.loadAsync(this.filepath);
+      this.#state = await JsonFile.loadAsync(this.filepath);
     } catch (error) {
       if (FileSystem.isNotExistError(error as Error)) {
-        this._state = undefined;
+        this.#state = undefined;
       } else {
         // This should not happen
         throw new InternalError(error);
       }
     }
-    return this._state;
+    return this.#state;
   }
 }
diff --git a/libraries/rush-lib/src/logic/operations/PeriodicCallback.ts b/libraries/rush-lib/src/logic/operations/PeriodicCallback.ts
index 26aa1814f55..8c645ef373b 100644
--- a/libraries/rush-lib/src/logic/operations/PeriodicCallback.ts
+++ b/libraries/rush-lib/src/logic/operations/PeriodicCallback.ts
@@ -13,42 +13,42 @@ export interface IPeriodicCallbackOptions {
  * @beta
  */
 export class PeriodicCallback {
-  private _callbacks: ICallbackFn[];
-  private _interval: number;
-  private _intervalId: NodeJS.Timeout | undefined;
-  private _isRunning: boolean;
+  #callbacks: ICallbackFn[];
+  #interval: number;
+  #intervalId: NodeJS.Timeout | undefined;
+  #isRunning: boolean;
 
   public constructor(options: IPeriodicCallbackOptions) {
-    this._callbacks = [];
-    this._interval = options.interval;
-    this._isRunning = false;
+    this.#callbacks = [];
+    this.#interval = options.interval;
+    this.#isRunning = false;
   }
 
   public addCallback(callback: ICallbackFn): void {
-    if (this._isRunning) {
+    if (this.#isRunning) {
       throw new Error('Can not add callback while watcher is running');
     }
-    this._callbacks.push(callback);
+    this.#callbacks.push(callback);
   }
 
   public start(): void {
-    if (this._intervalId) {
+    if (this.#intervalId) {
       throw new Error('Watcher already started');
     }
-    if (this._callbacks.length === 0) {
+    if (this.#callbacks.length === 0) {
       return;
     }
-    this._isRunning = true;
-    this._intervalId = setInterval(() => {
-      this._callbacks.forEach((callback) => callback());
-    }, this._interval);
+    this.#isRunning = true;
+    this.#intervalId = setInterval(() => {
+      this.#callbacks.forEach((callback) => callback());
+    }, this.#interval);
   }
 
   public stop(): void {
-    if (this._intervalId) {
-      clearInterval(this._intervalId);
-      this._intervalId = undefined;
-      this._isRunning = false;
+    if (this.#intervalId) {
+      clearInterval(this.#intervalId);
+      this.#intervalId = undefined;
+      this.#isRunning = false;
     }
   }
 }
diff --git a/libraries/rush-lib/src/logic/operations/PnpmSyncCopyOperationPlugin.ts b/libraries/rush-lib/src/logic/operations/PnpmSyncCopyOperationPlugin.ts
index 6857acf1ec0..ba47d2e4a6f 100644
--- a/libraries/rush-lib/src/logic/operations/PnpmSyncCopyOperationPlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/PnpmSyncCopyOperationPlugin.ts
@@ -16,10 +16,10 @@ import { RushConstants } from '../RushConstants';
 const PLUGIN_NAME: 'PnpmSyncCopyOperationPlugin' = 'PnpmSyncCopyOperationPlugin';
 
 export class PnpmSyncCopyOperationPlugin implements IPhasedCommandPlugin {
-  private readonly _terminal: ITerminal;
+  readonly #terminal: ITerminal;
 
   public constructor(terminal: ITerminal) {
-    this._terminal = terminal;
+    this.#terminal = terminal;
   }
   public apply(hooks: PhasedCommandHooks): void {
     hooks.onGraphCreatedAsync.tap(PLUGIN_NAME, (graph) => {
@@ -53,7 +53,7 @@ export class PnpmSyncCopyOperationPlugin implements IPhasedCommandPlugin {
               forEachAsyncWithConcurrency: Async.forEachAsync,
               getPackageIncludedFiles: PackageExtractor.getPackageIncludedFilesAsync,
               logMessageCallback: (logMessageOptions: ILogMessageCallbackOptions) =>
-                PnpmSyncUtilities.processLogMessage(logMessageOptions, this._terminal)
+                PnpmSyncUtilities.processLogMessage(logMessageOptions, this.#terminal)
             });
           }
         }
diff --git a/libraries/rush-lib/src/logic/operations/ProjectLogWritable.ts b/libraries/rush-lib/src/logic/operations/ProjectLogWritable.ts
index c11888a6b0d..7a9d4e4e6b7 100644
--- a/libraries/rush-lib/src/logic/operations/ProjectLogWritable.ts
+++ b/libraries/rush-lib/src/logic/operations/ProjectLogWritable.ts
@@ -93,19 +93,19 @@ const LOG_CHUNKS_FOLDER_RELATIVE_PATH: string = `${RushConstants.projectRushFold
 export class JsonLFileWritable extends TerminalWritable {
   public readonly logPath: string;
 
-  private _writer: FileWriter | undefined;
+  #writer: FileWriter | undefined;
 
   public constructor(logPath: string) {
     super();
 
     this.logPath = logPath;
 
-    this._writer = FileWriter.open(logPath);
+    this.#writer = FileWriter.open(logPath);
   }
 
   // Override writeChunk function to throw custom error
   public override writeChunk(chunk: ITerminalChunk): void {
-    if (!this._writer) {
+    if (!this.#writer) {
       throw new InternalError(`Log writer was closed for ${this.logPath}`);
     }
     // Stderr can always get written to a error log writer
@@ -113,20 +113,20 @@ export class JsonLFileWritable extends TerminalWritable {
   }
 
   protected onWriteChunk(chunk: ITerminalChunk): void {
-    if (!this._writer) {
+    if (!this.#writer) {
       throw new InternalError(`Log writer was closed for ${this.logPath}`);
     }
-    this._writer.write(JSON.stringify(chunk) + '\n');
+    this.#writer.write(JSON.stringify(chunk) + '\n');
   }
 
   protected override onClose(): void {
-    if (this._writer) {
+    if (this.#writer) {
       try {
-        this._writer.close();
+        this.#writer.close();
       } catch (error) {
-        throw new InternalError('Failed to close file handle for ' + this._writer.filePath);
+        throw new InternalError('Failed to close file handle for ' + this.#writer.filePath);
       }
-      this._writer = undefined;
+      this.#writer = undefined;
     }
   }
 }
@@ -138,8 +138,8 @@ export class SplitLogFileWritable extends TerminalWritable {
   public readonly logPath: string;
   public readonly errorLogPath: string;
 
-  private _logWriter: FileWriter | undefined = undefined;
-  private _errorLogWriter: FileWriter | undefined = undefined;
+  #logWriter: FileWriter | undefined = undefined;
+  #errorLogWriter: FileWriter | undefined = undefined;
 
   public constructor(logPath: string, errorLogPath: string) {
     super();
@@ -147,13 +147,13 @@ export class SplitLogFileWritable extends TerminalWritable {
     this.logPath = logPath;
     this.errorLogPath = errorLogPath;
 
-    this._logWriter = FileWriter.open(logPath);
-    this._errorLogWriter = undefined;
+    this.#logWriter = FileWriter.open(logPath);
+    this.#errorLogWriter = undefined;
   }
 
   // Override writeChunk function to throw custom error
   public override writeChunk(chunk: ITerminalChunk): void {
-    if (!this._logWriter) {
+    if (!this.#logWriter) {
       throw new InternalError(`Log writer was closed for ${this.logPath}`);
     }
     // Stderr can always get written to a error log writer
@@ -161,38 +161,38 @@ export class SplitLogFileWritable extends TerminalWritable {
   }
 
   protected onWriteChunk(chunk: ITerminalChunk): void {
-    if (!this._logWriter) {
+    if (!this.#logWriter) {
       throw new InternalError('Output file was closed');
     }
     // Both stderr and stdout get written to *.<phaseName>.log
-    this._logWriter.write(chunk.text);
+    this.#logWriter.write(chunk.text);
 
     if (chunk.kind === TerminalChunkKind.Stderr) {
       // Only stderr gets written to *.<phaseName>.error.log
-      if (!this._errorLogWriter) {
-        this._errorLogWriter = FileWriter.open(this.errorLogPath);
+      if (!this.#errorLogWriter) {
+        this.#errorLogWriter = FileWriter.open(this.errorLogPath);
       }
-      this._errorLogWriter.write(chunk.text);
+      this.#errorLogWriter.write(chunk.text);
     }
   }
 
   protected override onClose(): void {
-    if (this._logWriter) {
+    if (this.#logWriter) {
       try {
-        this._logWriter.close();
+        this.#logWriter.close();
       } catch (error) {
-        throw new InternalError('Failed to close file handle for ' + this._logWriter.filePath);
+        throw new InternalError('Failed to close file handle for ' + this.#logWriter.filePath);
       }
-      this._logWriter = undefined;
+      this.#logWriter = undefined;
     }
 
-    if (this._errorLogWriter) {
+    if (this.#errorLogWriter) {
       try {
-        this._errorLogWriter.close();
+        this.#errorLogWriter.close();
       } catch (error) {
-        throw new InternalError('Failed to close file handle for ' + this._errorLogWriter.filePath);
+        throw new InternalError('Failed to close file handle for ' + this.#errorLogWriter.filePath);
       }
-      this._errorLogWriter = undefined;
+      this.#errorLogWriter = undefined;
     }
   }
 }
diff --git a/libraries/rush-lib/src/logic/operations/ShellOperationRunner.ts b/libraries/rush-lib/src/logic/operations/ShellOperationRunner.ts
index a9de80dde28..ee511fd7d5d 100644
--- a/libraries/rush-lib/src/logic/operations/ShellOperationRunner.ts
+++ b/libraries/rush-lib/src/logic/operations/ShellOperationRunner.ts
@@ -41,13 +41,13 @@ export class ShellOperationRunner implements IOperationRunner {
    */
   public readonly isNoOp: boolean = false;
 
-  private readonly _commandForHash: string;
-  private readonly _initialCommand: string;
-  private readonly _incrementalCommand: string | undefined;
+  readonly #commandForHash: string;
+  readonly #initialCommand: string;
+  readonly #incrementalCommand: string | undefined;
 
-  private readonly _rushProject: RushConfigurationProject;
+  readonly #rushProject: RushConfigurationProject;
 
-  private readonly _ignoredParameterValues: ReadonlyArray<string>;
+  readonly #ignoredParameterValues: ReadonlyArray<string>;
 
   public constructor(options: IShellOperationRunnerOptions) {
     const {
@@ -63,11 +63,11 @@ export class ShellOperationRunner implements IOperationRunner {
     this.name = displayName;
     this.warningsAreAllowed =
       EnvironmentConfiguration.allowWarningsInSuccessfulBuild || phase.allowWarningsOnSuccess || false;
-    this._rushProject = rushProject;
-    this._initialCommand = initialCommand;
-    this._incrementalCommand = incrementalCommand;
-    this._commandForHash = commandForHash;
-    this._ignoredParameterValues = ignoredParameterValues;
+    this.#rushProject = rushProject;
+    this.#initialCommand = initialCommand;
+    this.#incrementalCommand = incrementalCommand;
+    this.#commandForHash = commandForHash;
+    this.#ignoredParameterValues = ignoredParameterValues;
   }
 
   public async executeAsync(
@@ -79,21 +79,21 @@ export class ShellOperationRunner implements IOperationRunner {
         let hasWarningOrError: boolean = false;
 
         // Log any ignored parameters
-        if (this._ignoredParameterValues.length > 0) {
+        if (this.#ignoredParameterValues.length > 0) {
           terminal.writeLine(
-            `These parameters were ignored for this operation by project-level configuration: ${this._ignoredParameterValues.join(' ')}`
+            `These parameters were ignored for this operation by project-level configuration: ${this.#ignoredParameterValues.join(' ')}`
           );
         }
         const incrementalCommand: string | undefined =
-          lastState && this._incrementalCommand ? this._incrementalCommand : undefined;
-        const commandToRun: string = incrementalCommand ?? this._initialCommand;
+          lastState && this.#incrementalCommand ? this.#incrementalCommand : undefined;
+        const commandToRun: string = incrementalCommand ?? this.#initialCommand;
 
         // Run the operation
         terminal.writeLine(
           `Invoking (${incrementalCommand !== undefined ? 'incremental' : 'initial'}): ${commandToRun}`
         );
 
-        const { rushConfiguration, projectFolder } = this._rushProject;
+        const { rushConfiguration, projectFolder } = this.#rushProject;
 
         const { environment: initialEnvironment } = context;
 
@@ -152,7 +152,7 @@ export class ShellOperationRunner implements IOperationRunner {
   }
 
   public getConfigHash(): string {
-    return this._commandForHash;
+    return this.#commandForHash;
   }
 }
 
diff --git a/libraries/rush-lib/src/logic/operations/ValidateOperationsPlugin.ts b/libraries/rush-lib/src/logic/operations/ValidateOperationsPlugin.ts
index 0f256c4789b..fcca1674973 100644
--- a/libraries/rush-lib/src/logic/operations/ValidateOperationsPlugin.ts
+++ b/libraries/rush-lib/src/logic/operations/ValidateOperationsPlugin.ts
@@ -14,10 +14,10 @@ const PLUGIN_NAME: 'ValidateOperationsPlugin' = 'ValidateOperationsPlugin';
  * Core phased command plugin that verifies correctness of the entries in rush-project.json
  */
 export class ValidateOperationsPlugin implements IPhasedCommandPlugin {
-  private readonly _terminal: ITerminal;
+  readonly #terminal: ITerminal;
 
   public constructor(terminal: ITerminal) {
-    this._terminal = terminal;
+    this.#terminal = terminal;
   }
 
   public apply(hooks: PhasedCommandHooks): void {
@@ -41,7 +41,7 @@ export class ValidateOperationsPlugin implements IPhasedCommandPlugin {
         const projectConfiguration: RushProjectConfiguration | undefined =
           context.projectConfigurations.get(project);
         if (projectConfiguration) {
-          projectConfiguration.validatePhaseConfiguration(phases, this._terminal);
+          projectConfiguration.validatePhaseConfiguration(phases, this.#terminal);
         }
       }
     });
diff --git a/libraries/rush-lib/src/logic/operations/test/MockOperationRunner.ts b/libraries/rush-lib/src/logic/operations/test/MockOperationRunner.ts
index 3e620634580..dc8444abeb0 100644
--- a/libraries/rush-lib/src/logic/operations/test/MockOperationRunner.ts
+++ b/libraries/rush-lib/src/logic/operations/test/MockOperationRunner.ts
@@ -7,7 +7,7 @@ import { OperationStatus } from '../OperationStatus';
 import type { IOperationRunner, IOperationRunnerContext } from '../IOperationRunner';
 
 export class MockOperationRunner implements IOperationRunner {
-  private readonly _action: ((terminal: CollatedTerminal) => Promise<OperationStatus>) | undefined;
+  readonly #action: ((terminal: CollatedTerminal) => Promise<OperationStatus>) | undefined;
   public readonly name: string;
   public readonly reportTiming: boolean = true;
   public readonly silent: boolean = false;
@@ -23,14 +23,14 @@ export class MockOperationRunner implements IOperationRunner {
   ) {
     this.isNoOp = isNoOp;
     this.name = name;
-    this._action = action;
+    this.#action = action;
     this.warningsAreAllowed = warningsAreAllowed;
   }
 
   public async executeAsync(context: IOperationRunnerContext): Promise<OperationStatus> {
     let result: OperationStatus | undefined;
-    if (this._action) {
-      result = await this._action(context.collatedWriter.terminal);
+    if (this.#action) {
+      result = await this.#action(context.collatedWriter.terminal);
     }
     return result || OperationStatus.Success;
   }
diff --git a/libraries/rush-lib/src/logic/pnpm/PnpmLinkManager.ts b/libraries/rush-lib/src/logic/pnpm/PnpmLinkManager.ts
index b020bea25af..d5b1d7bea20 100644
--- a/libraries/rush-lib/src/logic/pnpm/PnpmLinkManager.ts
+++ b/libraries/rush-lib/src/logic/pnpm/PnpmLinkManager.ts
@@ -35,7 +35,7 @@ import { IS_WINDOWS } from '../../utilities/executionUtilities';
 const DEBUG: boolean = false;
 
 export class PnpmLinkManager extends BaseLinkManager {
-  private readonly _pnpmVersion: semver.SemVer = new semver.SemVer(
+  readonly #pnpmVersion: semver.SemVer = new semver.SemVer(
     this._rushConfiguration.packageManagerToolVersion
   );
 
@@ -73,7 +73,7 @@ export class PnpmLinkManager extends BaseLinkManager {
       }
 
       for (const rushProject of this._rushConfiguration.projects) {
-        await this._linkProjectAsync(rushProject, pnpmShrinkwrapFile);
+        await this.#linkProjectAsync(rushProject, pnpmShrinkwrapFile);
       }
     } else {
       // eslint-disable-next-line no-console
@@ -91,7 +91,7 @@ export class PnpmLinkManager extends BaseLinkManager {
    * @param project             The local project that we will create symlinks for
    * @param rushLinkJson        The common/temp/rush-link.json output file
    */
-  private async _linkProjectAsync(
+  async #linkProjectAsync(
     project: RushConfigurationProject,
     pnpmShrinkwrapFile: PnpmShrinkwrapFile
   ): Promise<void> {
@@ -228,7 +228,7 @@ export class PnpmLinkManager extends BaseLinkManager {
         : '';
 
     // e.g.: C:\wbt\common\temp\node_modules\.local\C%3A%2Fwbt%2Fcommon%2Ftemp%2Fprojects%2Fapi-documenter.tgz\node_modules
-    const pathToLocalInstallation: string = await this._getPathToLocalInstallationAsync(
+    const pathToLocalInstallation: string = await this.#getPathToLocalInstallationAsync(
       tarballEntry,
       absolutePathToTgzFile,
       folderNameSuffix,
@@ -244,7 +244,7 @@ export class PnpmLinkManager extends BaseLinkManager {
     }
 
     for (const dependencyName of Object.keys(commonPackage.packageJson!.dependencies || {})) {
-      const newLocalPackage: BasePackage = this._createLocalPackageForDependency(
+      const newLocalPackage: BasePackage = this.#createLocalPackageForDependency(
         project,
         parentShrinkwrapEntry,
         localPackage,
@@ -289,13 +289,13 @@ export class PnpmLinkManager extends BaseLinkManager {
     });
   }
 
-  private async _getPathToLocalInstallationAsync(
+  async #getPathToLocalInstallationAsync(
     tarballEntry: string,
     absolutePathToTgzFile: string,
     folderSuffix: string,
     tempProjectDependencyKey: string
   ): Promise<string> {
-    if (this._pnpmVersion.major === 6) {
+    if (this.#pnpmVersion.major === 6) {
       // PNPM 6 changed formatting to replace all ':' and '/' chars with '+'. Additionally, folder names > 120
       // are trimmed and hashed. NOTE: PNPM internally uses fs.realpath.native, which will cause additional
       // issues in environments that do not support long paths.
@@ -323,7 +323,7 @@ export class PnpmLinkManager extends BaseLinkManager {
         folderName,
         RushConstants.nodeModulesFolderName
       );
-    } else if (this._pnpmVersion.major >= 10) {
+    } else if (this.#pnpmVersion.major >= 10) {
       const pnpmKitV10: typeof import('@rushstack/rush-pnpm-kit-v10') = await import(
         '@rushstack/rush-pnpm-kit-v10'
       );
@@ -343,7 +343,7 @@ export class PnpmLinkManager extends BaseLinkManager {
         folderName,
         RushConstants.nodeModulesFolderName
       );
-    } else if (this._pnpmVersion.major >= 9) {
+    } else if (this.#pnpmVersion.major >= 9) {
       const pnpmKitV9: typeof import('@rushstack/rush-pnpm-kit-v9') = await import(
         '@rushstack/rush-pnpm-kit-v9'
       );
@@ -359,7 +359,7 @@ export class PnpmLinkManager extends BaseLinkManager {
         folderName,
         RushConstants.nodeModulesFolderName
       );
-    } else if (this._pnpmVersion.major >= 8) {
+    } else if (this.#pnpmVersion.major >= 8) {
       const pnpmKitV8: typeof import('@rushstack/rush-pnpm-kit-v8') = await import(
         '@rushstack/rush-pnpm-kit-v8'
       );
@@ -376,7 +376,7 @@ export class PnpmLinkManager extends BaseLinkManager {
         folderName,
         RushConstants.nodeModulesFolderName
       );
-    } else if (this._pnpmVersion.major >= 7) {
+    } else if (this.#pnpmVersion.major >= 7) {
       const { depPathToFilename } = await import('dependency-path');
       // PNPM 7 changed the local path format again and the hashing algorithm
       // See https://github.com/pnpm/pnpm/releases/tag/v7.0.0
@@ -410,7 +410,7 @@ export class PnpmLinkManager extends BaseLinkManager {
       );
     }
   }
-  private _createLocalPackageForDependency(
+  #createLocalPackageForDependency(
     project: RushConfigurationProject,
     parentShrinkwrapEntry: IPnpmShrinkwrapDependencyYaml,
     localPackage: BasePackage,
diff --git a/libraries/rush-lib/src/logic/pnpm/PnpmOptionsConfiguration.ts b/libraries/rush-lib/src/logic/pnpm/PnpmOptionsConfiguration.ts
index f5c3b0481d5..79d38da2b7c 100644
--- a/libraries/rush-lib/src/logic/pnpm/PnpmOptionsConfiguration.ts
+++ b/libraries/rush-lib/src/logic/pnpm/PnpmOptionsConfiguration.ts
@@ -212,9 +212,9 @@ export interface IPnpmOptionsJson extends IPackageManagerOptionsJsonBase {
  * @public
  */
 export class PnpmOptionsConfiguration extends PackageManagerOptionsConfigurationBase {
-  private readonly _json: JsonObject;
-  private readonly _commonTempFolder: string;
-  private _globalPatchedDependencies: Record<string, string> | undefined;
+  readonly #json: JsonObject;
+  readonly #commonTempFolder: string;
+  #globalPatchedDependencies: Record<string, string> | undefined;
 
   /**
    * The method used to resolve the store used by PNPM.
@@ -553,13 +553,13 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
    * PNPM documentation: https://pnpm.io/package_json#pnpmpatcheddependencies
    */
   public get globalPatchedDependencies(): Record<string, string> | undefined {
-    return this._globalPatchedDependencies;
+    return this.#globalPatchedDependencies;
   }
 
   private constructor(json: IPnpmOptionsJson, commonTempFolder: string, jsonFilename?: string) {
     super(json);
-    this._json = json;
-    this._commonTempFolder = commonTempFolder;
+    this.#json = json;
+    this.#commonTempFolder = commonTempFolder;
     this.jsonFilename = jsonFilename;
     this.pnpmStore = json.pnpmStore || 'local';
     if (EnvironmentConfiguration.pnpmStorePathOverride) {
@@ -588,7 +588,7 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
     this.globalIgnoredOptionalDependencies = json.globalIgnoredOptionalDependencies;
     this.globalAllowedDeprecatedVersions = json.globalAllowedDeprecatedVersions;
     this.unsupportedPackageJsonSettings = json.unsupportedPackageJsonSettings;
-    this._globalPatchedDependencies = json.globalPatchedDependencies;
+    this.#globalPatchedDependencies = json.globalPatchedDependencies;
     this.resolutionMode = json.resolutionMode;
     this.autoInstallPeers = json.autoInstallPeers;
 
@@ -638,7 +638,7 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
     return new PnpmOptionsConfiguration(json, commonTempFolder);
   }
 
-  private _getJsonFilenameOrThrow(): string {
+  #getJsonFilenameOrThrow(): string {
     if (!this.jsonFilename) {
       throw new Error('Cannot save pnpm-config.json because no jsonFilename was provided.');
     }
@@ -660,16 +660,16 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
       const normalized: Record<string, string> = {};
       for (const [dependency, patchPath] of Object.entries(patchedDependencies)) {
         normalized[dependency] =
-          path.isAbsolute(patchPath) && Path.isUnder(patchPath, this._commonTempFolder)
-            ? Path.convertToSlashes(path.relative(this._commonTempFolder, patchPath))
+          path.isAbsolute(patchPath) && Path.isUnder(patchPath, this.#commonTempFolder)
+            ? Path.convertToSlashes(path.relative(this.#commonTempFolder, patchPath))
             : patchPath;
       }
       patchedDependencies = normalized;
     }
 
-    this._globalPatchedDependencies = patchedDependencies;
-    this._json.globalPatchedDependencies = patchedDependencies;
-    JsonFile.save(this._json, this._getJsonFilenameOrThrow(), {
+    this.#globalPatchedDependencies = patchedDependencies;
+    this.#json.globalPatchedDependencies = patchedDependencies;
+    JsonFile.save(this.#json, this.#getJsonFilenameOrThrow(), {
       updateExistingFile: true,
       ignoreUndefinedValues: true
     });
@@ -681,9 +681,9 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
    * @deprecated Use {@link PnpmOptionsConfiguration.updateGlobalOnlyBuiltDependenciesAsync} instead.
    */
   public updateGlobalOnlyBuiltDependencies(onlyBuiltDependencies: string[] | undefined): void {
-    this._json.globalOnlyBuiltDependencies = onlyBuiltDependencies;
+    this.#json.globalOnlyBuiltDependencies = onlyBuiltDependencies;
     if (this.jsonFilename) {
-      JsonFile.save(this._json, this.jsonFilename, {
+      JsonFile.save(this.#json, this.jsonFilename, {
         updateExistingFile: true,
         ignoreUndefinedValues: true
       });
@@ -696,8 +696,8 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
   public async updateGlobalOnlyBuiltDependenciesAsync(
     onlyBuiltDependencies: string[] | undefined
   ): Promise<void> {
-    this._json.globalOnlyBuiltDependencies = onlyBuiltDependencies;
-    await JsonFile.saveAsync(this._json, this._getJsonFilenameOrThrow(), {
+    this.#json.globalOnlyBuiltDependencies = onlyBuiltDependencies;
+    await JsonFile.saveAsync(this.#json, this.#getJsonFilenameOrThrow(), {
       updateExistingFile: true,
       ignoreUndefinedValues: true
     });
@@ -709,8 +709,8 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
   public async updateGlobalCatalogsAsync(
     catalogs: Record<string, Record<string, string>> | undefined
   ): Promise<void> {
-    this._json.globalCatalogs = catalogs;
-    await JsonFile.saveAsync(this._json, this._getJsonFilenameOrThrow(), {
+    this.#json.globalCatalogs = catalogs;
+    await JsonFile.saveAsync(this.#json, this.#getJsonFilenameOrThrow(), {
       updateExistingFile: true,
       ignoreUndefinedValues: true
     });
@@ -720,9 +720,9 @@ export class PnpmOptionsConfiguration extends PackageManagerOptionsConfiguration
    * Updates globalAllowBuilds field of the PNPM options in the common/config/rush/pnpm-config.json file.
    */
   public updateGlobalAllowBuilds(allowBuilds: Record<string, boolean> | undefined): void {
-    this._json.globalAllowBuilds = allowBuilds;
+    this.#json.globalAllowBuilds = allowBuilds;
     if (this.jsonFilename) {
-      JsonFile.save(this._json, this.jsonFilename, { updateExistingFile: true });
+      JsonFile.save(this.#json, this.jsonFilename, { updateExistingFile: true });
     }
   }
 }
diff --git a/libraries/rush-lib/src/logic/pnpm/PnpmProjectShrinkwrapFile.ts b/libraries/rush-lib/src/logic/pnpm/PnpmProjectShrinkwrapFile.ts
index 19e3899804c..07c54476590 100644
--- a/libraries/rush-lib/src/logic/pnpm/PnpmProjectShrinkwrapFile.ts
+++ b/libraries/rush-lib/src/logic/pnpm/PnpmProjectShrinkwrapFile.ts
@@ -107,18 +107,18 @@ export class PnpmProjectShrinkwrapFile extends BaseProjectShrinkwrapFile<PnpmShr
       if (name.indexOf(`${RushConstants.rushTempNpmScope}/`) < 0) {
         // Only select the shrinkwrap dependencies that are non-local since we already handle local
         // project changes
-        this._addDependencyRecursive(projectShrinkwrapMap, name, version, parentShrinkwrapEntry);
+        this.#addDependencyRecursive(projectShrinkwrapMap, name, version, parentShrinkwrapEntry);
       }
     }
 
     // Since peer dependencies within on external packages may be hoisted up to the top-level package,
     // we need to resolve and add these dependencies directly
-    this._resolveAndAddPeerDependencies(projectShrinkwrapMap, parentShrinkwrapEntry);
+    this.#resolveAndAddPeerDependencies(projectShrinkwrapMap, parentShrinkwrapEntry);
 
     return projectShrinkwrapMap;
   }
 
-  private _addDependencyRecursive(
+  #addDependencyRecursive(
     projectShrinkwrapMap: Map<string, string>,
     name: string,
     version: IPnpmVersionSpecifier,
@@ -159,14 +159,14 @@ export class PnpmProjectShrinkwrapFile extends BaseProjectShrinkwrapFile<PnpmShr
 
     // Add the dependencies of the dependency
     for (const [dependencyName, dependencyVersion] of Object.entries(shrinkwrapEntry.dependencies || {})) {
-      this._addDependencyRecursive(projectShrinkwrapMap, dependencyName, dependencyVersion, shrinkwrapEntry);
+      this.#addDependencyRecursive(projectShrinkwrapMap, dependencyName, dependencyVersion, shrinkwrapEntry);
     }
 
     // Add the optional dependencies of the dependency, and don't blow up if they don't exist
     for (const [dependencyName, dependencyVersion] of Object.entries(
       shrinkwrapEntry.optionalDependencies || {}
     )) {
-      this._addDependencyRecursive(
+      this.#addDependencyRecursive(
         projectShrinkwrapMap,
         dependencyName,
         dependencyVersion,
@@ -180,11 +180,11 @@ export class PnpmProjectShrinkwrapFile extends BaseProjectShrinkwrapFile<PnpmShr
     // is no need to look for peer dependencies, since it is simply a constraint to be validated by the
     // package manager.
     if (!this.shrinkwrapFile.isWorkspaceCompatible) {
-      this._resolveAndAddPeerDependencies(projectShrinkwrapMap, shrinkwrapEntry, parentShrinkwrapEntry);
+      this.#resolveAndAddPeerDependencies(projectShrinkwrapMap, shrinkwrapEntry, parentShrinkwrapEntry);
     }
   }
 
-  private _resolveAndAddPeerDependencies(
+  #resolveAndAddPeerDependencies(
     projectShrinkwrapMap: Map<string, string>,
     shrinkwrapEntry: IPnpmShrinkwrapDependencyYaml,
     parentShrinkwrapEntry?: IPnpmShrinkwrapDependencyYaml
@@ -215,7 +215,7 @@ export class PnpmProjectShrinkwrapFile extends BaseProjectShrinkwrapFile<PnpmShr
         this.shrinkwrapFile.getTopLevelDependencyVersion(peerDependencyName);
 
       if (topLevelDependencySpecifier) {
-        this._addDependencyRecursive(
+        this.#addDependencyRecursive(
           projectShrinkwrapMap,
           peerDependencyName,
           this.shrinkwrapFile.getTopLevelDependencyKey(peerDependencyName)!,
diff --git a/libraries/rush-lib/src/logic/pnpm/PnpmShrinkwrapFile.ts b/libraries/rush-lib/src/logic/pnpm/PnpmShrinkwrapFile.ts
index 515d416ea09..686086cac89 100644
--- a/libraries/rush-lib/src/logic/pnpm/PnpmShrinkwrapFile.ts
+++ b/libraries/rush-lib/src/logic/pnpm/PnpmShrinkwrapFile.ts
@@ -323,14 +323,14 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
   public readonly packageExtensionsChecksum: undefined | string;
   public readonly hash: string;
 
-  private readonly _shrinkwrapJson: IPnpmShrinkwrapYaml;
-  private readonly _integrities: Map<string, Map<string, string>>;
-  private _pnpmfileConfiguration: PnpmfileConfiguration | undefined;
+  readonly #shrinkwrapJson: IPnpmShrinkwrapYaml;
+  readonly #integrities: Map<string, Map<string, string>>;
+  #pnpmfileConfiguration: PnpmfileConfiguration | undefined;
 
   private constructor(shrinkwrapJson: IPnpmShrinkwrapYaml, hash: string, subspaceHasNoProjects: boolean) {
     super();
     this.hash = hash;
-    this._shrinkwrapJson = shrinkwrapJson;
+    this.#shrinkwrapJson = shrinkwrapJson;
     cacheByLockfileHash.set(hash, this);
 
     // Normalize the data
@@ -371,7 +371,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
 
     this.isWorkspaceCompatible = isWorkspaceCompatible;
 
-    this._integrities = new Map();
+    this.#integrities = new Map();
   }
 
   public static getLockfileV9PackageId(name: string, version: string): string {
@@ -466,7 +466,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     // when computing the hash, since the main concern is changes to the overall external dependency footprint
     const { omitImportersFromPreventManualShrinkwrapChanges } = experimentsConfig || {};
 
-    const shrinkwrapContent: string = this._serializeInternal(
+    const shrinkwrapContent: string = this.#serializeInternal(
       omitImportersFromPreventManualShrinkwrapChanges
     );
     return crypto.createHash('sha1').update(shrinkwrapContent).digest('hex');
@@ -476,7 +476,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
    * Determine whether `pnpm-lock.yaml` contains insecure sha1 hashes.
    * @internal
    */
-  private _disallowInsecureSha1(
+  #disallowInsecureSha1(
     customTipsConfiguration: CustomTipsConfiguration,
     exemptPackageVersions: Record<string, string[]>,
     terminal: ITerminal,
@@ -485,14 +485,14 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     const exemptPackageList: Map<string, boolean> = new Map();
     for (const [pkgName, versions] of Object.entries(exemptPackageVersions)) {
       for (const version of versions) {
-        exemptPackageList.set(this._getPackageId(pkgName, version), true);
+        exemptPackageList.set(this.#getPackageId(pkgName, version), true);
       }
     }
 
     for (const [pkgName, { resolution }] of this.packages) {
       if (
         resolution?.integrity?.startsWith('sha1') &&
-        !exemptPackageList.has(this._parseDependencyPath(pkgName))
+        !exemptPackageList.has(this.#parseDependencyPath(pkgName))
       ) {
         terminal.writeErrorLine(
           'Error: An integrity field with "sha1" was detected in the pnpm-lock.yaml file located in subspace ' +
@@ -518,7 +518,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     let invalidPoliciesCount: number = 0;
 
     if (pnpmLockfilePolicies?.disallowInsecureSha1?.enabled) {
-      const isError: boolean = this._disallowInsecureSha1(
+      const isError: boolean = this.#disallowInsecureSha1(
         rushConfiguration.customTipsConfiguration,
         pnpmLockfilePolicies.disallowInsecureSha1.exemptPackageVersions,
         terminal,
@@ -589,7 +589,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
    * This operation exactly mirrors the behavior of PNPM's own implementation:
    * https://github.com/pnpm/pnpm/blob/73ebfc94e06d783449579cda0c30a40694d210e4/lockfile/lockfile-file/src/experiments/inlineSpecifiersLockfileConverters.ts#L162
    */
-  private _convertLockfileV6DepPathToV5DepPath(newDepPath: string): string {
+  #convertLockfileV6DepPathToV5DepPath(newDepPath: string): string {
     if (!newDepPath.includes('@', 2) || newDepPath.startsWith('file:')) return newDepPath;
     const index: number = newDepPath.indexOf('@', newDepPath.indexOf('/@') + 2);
     if (newDepPath.includes('(') && index > pnpmKitV8.dependencyPath.indexOfPeersSuffix(newDepPath))
@@ -602,7 +602,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
    * Example: "/eslint-utils@3.0.0(eslint@8.23.1)" --> "/eslint-utils@3.0.0"
    * Example: "/@typescript-eslint/experimental-utils/5.9.1_eslint@8.6.0+typescript@4.4.4" --> "/@typescript-eslint/experimental-utils/5.9.1"
    */
-  private _parseDependencyPath(packagePath: string): string {
+  #parseDependencyPath(packagePath: string): string {
     let name: string | undefined;
     let version: string | undefined;
 
@@ -616,7 +616,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
       ({ name, version } = pnpmKitV9.dependencyPath.parse(packagePath));
     } else {
       if (this.shrinkwrapFileMajorVersion >= ShrinkwrapFileMajorVersion.V6) {
-        packagePath = this._convertLockfileV6DepPathToV5DepPath(packagePath);
+        packagePath = this.#convertLockfileV6DepPathToV5DepPath(packagePath);
       }
 
       ({ name, version } = pnpmKitV8.dependencyPath.parse(packagePath));
@@ -626,11 +626,11 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
       throw new InternalError(`Unable to parse package path: ${packagePath}`);
     }
 
-    return this._getPackageId(name, version);
+    return this.#getPackageId(name, version);
   }
 
   public override getTempProjectNames(): ReadonlyArray<string> {
-    return this._getTempProjectNames(this._shrinkwrapJson.dependencies || {});
+    return this._getTempProjectNames(this.#shrinkwrapJson.dependencies || {});
   }
 
   /**
@@ -798,7 +798,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     name: string,
     version: IPnpmVersionSpecifier
   ): IPnpmShrinkwrapDependencyYaml | undefined {
-    const packageId: string = this._getPackageId(name, version);
+    const packageId: string = this.#getPackageId(name, version);
     return this.packages.get(packageId);
   }
 
@@ -806,7 +806,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
    * Serializes the PNPM Shrinkwrap file
    */
   protected override serialize(): string {
-    return this._serializeInternal(false);
+    return this.#serializeInternal(false);
   }
 
   /**
@@ -834,7 +834,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     }
 
     const packageDescription: IPnpmShrinkwrapDependencyYaml | undefined =
-      this._getPackageDescription(tempProjectDependencyKey);
+      this.#getPackageDescription(tempProjectDependencyKey);
     if (
       !packageDescription ||
       !packageDescription.dependencies ||
@@ -844,7 +844,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     }
 
     const dependencyKey: IPnpmVersionSpecifier = packageDescription.dependencies[packageName];
-    return this._parsePnpmDependencyKey(packageName, dependencyKey);
+    return this.#parsePnpmDependencyKey(packageName, dependencyKey);
   }
 
   public override findOrphanedProjects(
@@ -896,13 +896,13 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
   public getIntegrityForImporter(importerKey: string): Map<string, string> | undefined {
     // This logic formerly lived in PnpmProjectShrinkwrapFile. Moving it here allows caching of the external
     // dependency integrity relationships across projects
-    let integrityMap: Map<string, string> | undefined = this._integrities.get(importerKey);
+    let integrityMap: Map<string, string> | undefined = this.#integrities.get(importerKey);
     if (!integrityMap) {
       const importer: IPnpmShrinkwrapImporterYaml | undefined = this.getImporter(importerKey);
       if (importer) {
         const resolvedIntegrityMap: Map<string, string> = new Map();
         integrityMap = resolvedIntegrityMap;
-        this._integrities.set(importerKey, resolvedIntegrityMap);
+        this.#integrities.set(importerKey, resolvedIntegrityMap);
 
         const sha256Digest: string = crypto
           .createHash('sha256')
@@ -938,7 +938,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
               externalDeps[name] = versionSpecifier;
             }
           }
-          this._addIntegrities(resolvedIntegrityMap, externalDeps, optional);
+          this.#addIntegrities(resolvedIntegrityMap, externalDeps, optional);
         };
 
         if (dependencies) {
@@ -977,8 +977,8 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     const packageJson: IPackageJson = project.packageJsonEditor.saveToObject();
 
     // Initialize the pnpmfile if it doesn't exist
-    if (!this._pnpmfileConfiguration) {
-      this._pnpmfileConfiguration = await PnpmfileConfiguration.initializeAsync(
+    if (!this.#pnpmfileConfiguration) {
+      this.#pnpmfileConfiguration = await PnpmfileConfiguration.initializeAsync(
         project.rushConfiguration,
         subspace,
         variant
@@ -1044,7 +1044,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     // Use a new PackageJsonEditor since it will classify each dependency type, making tracking the
     // found versions much simpler.
     const { dependencyList, devDependencyList, dependencyMetaList } = PackageJsonEditor.fromObject(
-      this._pnpmfileConfiguration.transform(transformedPackageJson),
+      this.#pnpmfileConfiguration.transform(transformedPackageJson),
       project.packageJsonEditor.filePath
     );
 
@@ -1233,8 +1233,8 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     return false;
   }
 
-  private _getIntegrityForPackage(specifier: string, optional: boolean): Map<string, string> {
-    const integrities: Map<string, Map<string, string>> = this._integrities;
+  #getIntegrityForPackage(specifier: string, optional: boolean): Map<string, string> {
+    const integrities: Map<string, Map<string, string>> = this.#integrities;
 
     let integrityMap: Map<string, string> | undefined = integrities.get(specifier);
     if (integrityMap) {
@@ -1271,17 +1271,17 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     const { dependencies, optionalDependencies } = shrinkwrapEntry;
 
     if (dependencies) {
-      this._addIntegrities(integrityMap, dependencies, false);
+      this.#addIntegrities(integrityMap, dependencies, false);
     }
 
     if (optionalDependencies) {
-      this._addIntegrities(integrityMap, optionalDependencies, true);
+      this.#addIntegrities(integrityMap, optionalDependencies, true);
     }
 
     return integrityMap;
   }
 
-  private _addIntegrities(
+  #addIntegrities(
     integrityMap: Map<string, string>,
     collection: Record<string, IPnpmVersionSpecifier>,
     optional: boolean
@@ -1300,13 +1300,13 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
           }
         }
       } else {
-        const packageId: string = this._getPackageId(name, version);
+        const packageId: string = this.#getPackageId(name, version);
         if (integrityMap.has(packageId)) {
           // The entry could already have been added as a nested dependency
           continue;
         }
 
-        const contribution: Map<string, string> = this._getIntegrityForPackage(packageId, optional);
+        const contribution: Map<string, string> = this.#getIntegrityForPackage(packageId, optional);
         for (const [dep, integrity] of contribution) {
           integrityMap.set(dep, integrity);
         }
@@ -1317,7 +1317,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
   /**
    * Gets the package description for a tempProject from the shrinkwrap file.
    */
-  private _getPackageDescription(
+  #getPackageDescription(
     tempProjectDependencyKey: string
   ): IPnpmShrinkwrapDependencyYaml | undefined {
     const packageDescription: IPnpmShrinkwrapDependencyYaml | undefined =
@@ -1326,7 +1326,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     return packageDescription && packageDescription.dependencies ? packageDescription : undefined;
   }
 
-  private _getPackageId(name: string, versionSpecifier: IPnpmVersionSpecifier): string {
+  #getPackageId(name: string, versionSpecifier: IPnpmVersionSpecifier): string {
     const version: string = normalizePnpmVersionSpecifier(versionSpecifier);
     if (this.shrinkwrapFileMajorVersion >= ShrinkwrapFileMajorVersion.V9) {
       return PnpmShrinkwrapFile.getLockfileV9PackageId(name, version);
@@ -1343,7 +1343,7 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     }
   }
 
-  private _parsePnpmDependencyKey(
+  #parsePnpmDependencyKey(
     dependencyName: string,
     pnpmDependencyKey: IPnpmVersionSpecifier
   ): DependencySpecifier | undefined {
@@ -1366,11 +1366,11 @@ export class PnpmShrinkwrapFile extends BaseShrinkwrapFile {
     }
   }
 
-  private _serializeInternal(omitImporters: boolean = false): string {
+  #serializeInternal(omitImporters: boolean = false): string {
     // Ensure that if any of the top-level properties are provided but empty are removed. We populate the object
     // properties when we read the shrinkwrap but PNPM does not set these top-level properties unless they are present.
     const shrinkwrapToSerialize: { [key: string]: unknown } = {};
-    for (const [key, value] of Object.entries(this._shrinkwrapJson)) {
+    for (const [key, value] of Object.entries(this.#shrinkwrapJson)) {
       if (omitImporters && key === 'importers') {
         continue;
       }
diff --git a/libraries/rush-lib/src/logic/pnpm/PnpmWorkspaceFile.ts b/libraries/rush-lib/src/logic/pnpm/PnpmWorkspaceFile.ts
index 7734ee575e1..433ac3d699c 100644
--- a/libraries/rush-lib/src/logic/pnpm/PnpmWorkspaceFile.ts
+++ b/libraries/rush-lib/src/logic/pnpm/PnpmWorkspaceFile.ts
@@ -128,7 +128,7 @@ export class PnpmWorkspaceFile extends BaseWorkspaceFile {
    */
   public readonly workspaceFilename: string;
 
-  private readonly _workspacePackages: Set<string>;
+  readonly #workspacePackages: Set<string>;
   public catalogs: IPnpmWorkspaceYaml['catalogs'];
   public allowBuilds: IPnpmWorkspaceYaml['allowBuilds'];
   public overrides: IPnpmWorkspaceYaml['overrides'];
@@ -154,7 +154,7 @@ export class PnpmWorkspaceFile extends BaseWorkspaceFile {
     this.workspaceFilename = workspaceYamlFilename;
     // Ignore any existing file since this file is generated and we need to handle deleting packages
     // If we need to support manual customization, that should be an additional parameter for "base file"
-    this._workspacePackages = new Set<string>();
+    this.#workspacePackages = new Set<string>();
   }
 
   /**
@@ -230,12 +230,12 @@ export class PnpmWorkspaceFile extends BaseWorkspaceFile {
 
     // Glob can't handle Windows paths
     const globPath: string = Path.convertToSlashes(packagePath);
-    this._workspacePackages.add(globEscape(globPath));
+    this.#workspacePackages.add(globEscape(globPath));
   }
 
   protected override async serializeAsync(): Promise<string> {
+    const workspacePackages: Set<string> = this.#workspacePackages;
     const {
-      _workspacePackages: workspacePackages,
       catalogs,
       allowBuilds,
       overrides,
diff --git a/libraries/rush-lib/src/logic/pnpm/PnpmfileConfiguration.ts b/libraries/rush-lib/src/logic/pnpm/PnpmfileConfiguration.ts
index 0db2eb38807..8f2c4cebebf 100644
--- a/libraries/rush-lib/src/logic/pnpm/PnpmfileConfiguration.ts
+++ b/libraries/rush-lib/src/logic/pnpm/PnpmfileConfiguration.ts
@@ -21,11 +21,11 @@ import type { Subspace } from '../../api/Subspace';
  * optionally utilizing a pnpmfile shim to inject preferred versions.
  */
 export class PnpmfileConfiguration {
-  private _context: IPnpmfileContext | undefined;
+  #context: IPnpmfileContext | undefined;
 
   private constructor(context: IPnpmfileContext) {
     pnpmfile.reset();
-    this._context = context;
+    this.#context = context;
   }
 
   public static async initializeAsync(
@@ -88,10 +88,10 @@ export class PnpmfileConfiguration {
    * @returns the transformed object, or the original input if pnpmfile.js was not found.
    */
   public transform(packageJson: IPackageJson): IPackageJson {
-    if (!pnpmfile.hooks?.readPackage || !this._context) {
+    if (!pnpmfile.hooks?.readPackage || !this.#context) {
       return packageJson;
     } else {
-      return pnpmfile.hooks.readPackage(packageJson, this._context);
+      return pnpmfile.hooks.readPackage(packageJson, this.#context);
     }
   }
 }
diff --git a/libraries/rush-lib/src/logic/selectors/GitChangedProjectSelectorParser.ts b/libraries/rush-lib/src/logic/selectors/GitChangedProjectSelectorParser.ts
index 65d7b40fae5..ee5095fd241 100644
--- a/libraries/rush-lib/src/logic/selectors/GitChangedProjectSelectorParser.ts
+++ b/libraries/rush-lib/src/logic/selectors/GitChangedProjectSelectorParser.ts
@@ -21,30 +21,30 @@ export interface IGitSelectorParserOptions {
 }
 
 export class GitChangedProjectSelectorParser implements ISelectorParser<RushConfigurationProject> {
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _options: IGitSelectorParserOptions;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #options: IGitSelectorParserOptions;
 
   public constructor(rushConfiguration: RushConfiguration, options: IGitSelectorParserOptions) {
-    this._rushConfiguration = rushConfiguration;
-    this._options = options;
+    this.#rushConfiguration = rushConfiguration;
+    this.#options = options;
   }
 
   public async evaluateSelectorAsync({
     unscopedSelector,
     terminal
   }: IEvaluateSelectorOptions): Promise<Iterable<RushConfigurationProject>> {
-    const projectChangeAnalyzer: ProjectChangeAnalyzer = new ProjectChangeAnalyzer(this._rushConfiguration);
+    const projectChangeAnalyzer: ProjectChangeAnalyzer = new ProjectChangeAnalyzer(this.#rushConfiguration);
 
     const options: IGetChangedProjectsOptions = {
       terminal,
       targetBranchName: unscopedSelector,
-      ...this._options
+      ...this.#options
     };
 
     return await projectChangeAnalyzer.getChangedProjectsAsync(options);
   }
 
   public getCompletions(): Iterable<string> {
-    return [this._rushConfiguration.repositoryDefaultBranch, 'HEAD~1', 'HEAD'];
+    return [this.#rushConfiguration.repositoryDefaultBranch, 'HEAD~1', 'HEAD'];
   }
 }
diff --git a/libraries/rush-lib/src/logic/selectors/NamedProjectSelectorParser.ts b/libraries/rush-lib/src/logic/selectors/NamedProjectSelectorParser.ts
index b39ab7ffe96..536c07648ff 100644
--- a/libraries/rush-lib/src/logic/selectors/NamedProjectSelectorParser.ts
+++ b/libraries/rush-lib/src/logic/selectors/NamedProjectSelectorParser.ts
@@ -9,10 +9,10 @@ import type { IEvaluateSelectorOptions, ISelectorParser } from './ISelectorParse
 import { RushConstants } from '../RushConstants';
 
 export class NamedProjectSelectorParser implements ISelectorParser<RushConfigurationProject> {
-  private readonly _rushConfiguration: RushConfiguration;
+  readonly #rushConfiguration: RushConfiguration;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   public async evaluateSelectorAsync({
@@ -21,7 +21,7 @@ export class NamedProjectSelectorParser implements ISelectorParser<RushConfigura
     parameterName
   }: IEvaluateSelectorOptions): Promise<Iterable<RushConfigurationProject>> {
     const project: RushConfigurationProject | undefined =
-      this._rushConfiguration.findProjectByShorthandName(unscopedSelector);
+      this.#rushConfiguration.findProjectByShorthandName(unscopedSelector);
     if (!project) {
       terminal.writeErrorLine(
         `The project name "${unscopedSelector}" passed to "${parameterName}" does not exist in ` +
@@ -37,7 +37,7 @@ export class NamedProjectSelectorParser implements ISelectorParser<RushConfigura
     const unscopedNamesMap: Map<string, number> = new Map<string, number>();
 
     const scopedNames: Set<string> = new Set();
-    for (const project of this._rushConfiguration.rushConfigurationJson.projects) {
+    for (const project of this.#rushConfiguration.rushConfigurationJson.projects) {
       scopedNames.add(project.packageName);
       const unscopedName: string = PackageName.getUnscopedName(project.packageName);
       const count: number = unscopedNamesMap.get(unscopedName) || 0;
diff --git a/libraries/rush-lib/src/logic/selectors/PathProjectSelectorParser.ts b/libraries/rush-lib/src/logic/selectors/PathProjectSelectorParser.ts
index eb91e176b2d..97c2136bc72 100644
--- a/libraries/rush-lib/src/logic/selectors/PathProjectSelectorParser.ts
+++ b/libraries/rush-lib/src/logic/selectors/PathProjectSelectorParser.ts
@@ -12,12 +12,12 @@ import type { IEvaluateSelectorOptions, ISelectorParser } from './ISelectorParse
 import { RushConstants } from '../RushConstants';
 
 export class PathProjectSelectorParser implements ISelectorParser<RushConfigurationProject> {
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _workingDirectory: string;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #workingDirectory: string;
 
   public constructor(rushConfiguration: RushConfiguration, workingDirectory: string) {
-    this._rushConfiguration = rushConfiguration;
-    this._workingDirectory = workingDirectory;
+    this.#rushConfiguration = rushConfiguration;
+    this.#workingDirectory = workingDirectory;
   }
 
   public async evaluateSelectorAsync({
@@ -26,17 +26,17 @@ export class PathProjectSelectorParser implements ISelectorParser<RushConfigurat
     parameterName
   }: IEvaluateSelectorOptions): Promise<Iterable<RushConfigurationProject>> {
     // Resolve the input path against the working directory
-    const absolutePath: string = nodePath.resolve(this._workingDirectory, unscopedSelector);
+    const absolutePath: string = nodePath.resolve(this.#workingDirectory, unscopedSelector);
 
     // Relativize it to the rushJsonFolder
-    const relativePath: string = nodePath.relative(this._rushConfiguration.rushJsonFolder, absolutePath);
+    const relativePath: string = nodePath.relative(this.#rushConfiguration.rushJsonFolder, absolutePath);
 
     // Normalize path separators to forward slashes for LookupByPath
     const normalizedPath: string = Path.convertToSlashes(relativePath);
 
     // Get the LookupByPath instance for the Rush root
     const lookupByPath: LookupByPath<RushConfigurationProject> =
-      this._rushConfiguration.getProjectLookupForRoot(this._rushConfiguration.rushJsonFolder);
+      this.#rushConfiguration.getProjectLookupForRoot(this.#rushConfiguration.rushJsonFolder);
 
     // Check if this path is within a project or matches a project exactly
     const containingProject: RushConfigurationProject | undefined =
diff --git a/libraries/rush-lib/src/logic/selectors/SubspaceSelectorParser.ts b/libraries/rush-lib/src/logic/selectors/SubspaceSelectorParser.ts
index f4b3a2bfd06..7abc26db991 100644
--- a/libraries/rush-lib/src/logic/selectors/SubspaceSelectorParser.ts
+++ b/libraries/rush-lib/src/logic/selectors/SubspaceSelectorParser.ts
@@ -8,16 +8,16 @@ import { RushConstants } from '../RushConstants';
 import type { IEvaluateSelectorOptions, ISelectorParser } from './ISelectorParser';
 
 export class SubspaceSelectorParser implements ISelectorParser<RushConfigurationProject> {
-  private readonly _rushConfiguration: RushConfiguration;
+  readonly #rushConfiguration: RushConfiguration;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   public async evaluateSelectorAsync({
     unscopedSelector
   }: IEvaluateSelectorOptions): Promise<Iterable<RushConfigurationProject>> {
-    const subspace: Subspace = this._rushConfiguration.getSubspace(unscopedSelector);
+    const subspace: Subspace = this.#rushConfiguration.getSubspace(unscopedSelector);
 
     return subspace.getProjects();
   }
@@ -25,8 +25,8 @@ export class SubspaceSelectorParser implements ISelectorParser<RushConfiguration
   public getCompletions(): Iterable<string> {
     // Tab completion is a performance sensitive operation, so avoid loading all the projects
     const subspaceNames: string[] = [];
-    if (this._rushConfiguration.subspacesConfiguration) {
-      subspaceNames.push(...this._rushConfiguration.subspacesConfiguration.subspaceNames);
+    if (this.#rushConfiguration.subspacesConfiguration) {
+      subspaceNames.push(...this.#rushConfiguration.subspacesConfiguration.subspaceNames);
     }
     if (!subspaceNames.indexOf(RushConstants.defaultSubspaceName)) {
       subspaceNames.push(RushConstants.defaultSubspaceName);
diff --git a/libraries/rush-lib/src/logic/selectors/TagProjectSelectorParser.ts b/libraries/rush-lib/src/logic/selectors/TagProjectSelectorParser.ts
index f704bb81edc..708803947a0 100644
--- a/libraries/rush-lib/src/logic/selectors/TagProjectSelectorParser.ts
+++ b/libraries/rush-lib/src/logic/selectors/TagProjectSelectorParser.ts
@@ -9,10 +9,10 @@ import type { IEvaluateSelectorOptions, ISelectorParser } from './ISelectorParse
 import { RushConstants } from '../RushConstants';
 
 export class TagProjectSelectorParser implements ISelectorParser<RushConfigurationProject> {
-  private readonly _rushConfiguration: RushConfiguration;
+  readonly #rushConfiguration: RushConfiguration;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   public async evaluateSelectorAsync({
@@ -21,7 +21,7 @@ export class TagProjectSelectorParser implements ISelectorParser<RushConfigurati
     parameterName
   }: IEvaluateSelectorOptions): Promise<Iterable<RushConfigurationProject>> {
     const selection: ReadonlySet<RushConfigurationProject> | undefined =
-      this._rushConfiguration.projectsByTag.get(unscopedSelector);
+      this.#rushConfiguration.projectsByTag.get(unscopedSelector);
     if (!selection) {
       terminal.writeErrorLine(
         `The tag "${unscopedSelector}" passed to "${parameterName}" is not specified for any projects in ` +
@@ -33,6 +33,6 @@ export class TagProjectSelectorParser implements ISelectorParser<RushConfigurati
   }
 
   public getCompletions(): Iterable<string> {
-    return this._rushConfiguration.projectsByTag.keys();
+    return this.#rushConfiguration.projectsByTag.keys();
   }
 }
diff --git a/libraries/rush-lib/src/logic/selectors/VersionPolicyProjectSelectorParser.ts b/libraries/rush-lib/src/logic/selectors/VersionPolicyProjectSelectorParser.ts
index c12c993afec..32c2e4c1a9f 100644
--- a/libraries/rush-lib/src/logic/selectors/VersionPolicyProjectSelectorParser.ts
+++ b/libraries/rush-lib/src/logic/selectors/VersionPolicyProjectSelectorParser.ts
@@ -8,10 +8,10 @@ import type { RushConfigurationProject } from '../../api/RushConfigurationProjec
 import type { IEvaluateSelectorOptions, ISelectorParser } from './ISelectorParser';
 
 export class VersionPolicyProjectSelectorParser implements ISelectorParser<RushConfigurationProject> {
-  private readonly _rushConfiguration: RushConfiguration;
+  readonly #rushConfiguration: RushConfiguration;
 
   public constructor(rushConfiguration: RushConfiguration) {
-    this._rushConfiguration = rushConfiguration;
+    this.#rushConfiguration = rushConfiguration;
   }
 
   public async evaluateSelectorAsync({
@@ -21,14 +21,14 @@ export class VersionPolicyProjectSelectorParser implements ISelectorParser<RushC
   }: IEvaluateSelectorOptions): Promise<Iterable<RushConfigurationProject>> {
     const selection: Set<RushConfigurationProject> = new Set();
 
-    if (!this._rushConfiguration.versionPolicyConfiguration.versionPolicies.has(unscopedSelector)) {
+    if (!this.#rushConfiguration.versionPolicyConfiguration.versionPolicies.has(unscopedSelector)) {
       terminal.writeErrorLine(
         `The version policy "${unscopedSelector}" passed to "${parameterName}" does not exist in version-policies.json.`
       );
       throw new AlreadyReportedError();
     }
 
-    for (const project of this._rushConfiguration.projects) {
+    for (const project of this.#rushConfiguration.projects) {
       if (project.versionPolicyName === unscopedSelector) {
         selection.add(project);
       }
@@ -38,6 +38,6 @@ export class VersionPolicyProjectSelectorParser implements ISelectorParser<RushC
   }
 
   public getCompletions(): Iterable<string> {
-    return this._rushConfiguration.versionPolicyConfiguration.versionPolicies.keys();
+    return this.#rushConfiguration.versionPolicyConfiguration.versionPolicies.keys();
   }
 }
diff --git a/libraries/rush-lib/src/logic/setup/ArtifactoryConfiguration.ts b/libraries/rush-lib/src/logic/setup/ArtifactoryConfiguration.ts
index effb502a5c9..3779c73ce90 100644
--- a/libraries/rush-lib/src/logic/setup/ArtifactoryConfiguration.ts
+++ b/libraries/rush-lib/src/logic/setup/ArtifactoryConfiguration.ts
@@ -38,7 +38,7 @@ const _jsonSchema: JsonSchema = JsonSchema.fromLoadedObject(schemaJson);
  * It configures the "rush setup" command.
  */
 export class ArtifactoryConfiguration {
-  private readonly _jsonFileName: string;
+  readonly #jsonFileName: string;
 
   /**
    * Get the artifactory configuration.
@@ -49,7 +49,7 @@ export class ArtifactoryConfiguration {
    * @internal
    */
   public constructor(jsonFileName: string) {
-    this._jsonFileName = jsonFileName;
+    this.#jsonFileName = jsonFileName;
 
     this.configuration = {
       packageRegistry: {
@@ -59,8 +59,8 @@ export class ArtifactoryConfiguration {
       }
     };
 
-    if (FileSystem.exists(this._jsonFileName)) {
-      this.configuration = JsonFile.loadAndValidate(this._jsonFileName, _jsonSchema);
+    if (FileSystem.exists(this.#jsonFileName)) {
+      this.configuration = JsonFile.loadAndValidate(this.#jsonFileName, _jsonSchema);
       if (!this.configuration.packageRegistry.credentialType) {
         this.configuration.packageRegistry.credentialType = 'password';
       }
diff --git a/libraries/rush-lib/src/logic/setup/KeyboardLoop.ts b/libraries/rush-lib/src/logic/setup/KeyboardLoop.ts
index 962dd2d5e68..ce795308f47 100644
--- a/libraries/rush-lib/src/logic/setup/KeyboardLoop.ts
+++ b/libraries/rush-lib/src/logic/setup/KeyboardLoop.ts
@@ -18,10 +18,10 @@ const ANSI_ESCAPE_HIDE_CURSOR: string = '\u001B[?25h';
 export class KeyboardLoop {
   protected stdin: NodeJS.ReadStream;
   protected stderr: NodeJS.WriteStream;
-  private _readlineInterface: readline.Interface | undefined;
-  private _resolvePromise: (() => void) | undefined;
-  private _rejectPromise: ((error: Error) => void) | undefined;
-  private _cursorHidden: boolean = false;
+  #readlineInterface: readline.Interface | undefined;
+  #resolvePromise: (() => void) | undefined;
+  #rejectPromise: ((error: Error) => void) | undefined;
+  #cursorHidden: boolean = false;
 
   public constructor() {
     this.stdin = process.stdin;
@@ -29,24 +29,24 @@ export class KeyboardLoop {
   }
 
   public get capturedInput(): boolean {
-    return this._readlineInterface !== undefined;
+    return this.#readlineInterface !== undefined;
   }
 
-  private _captureInput(): void {
-    if (this._readlineInterface) {
+  #captureInput(): void {
+    if (this.#readlineInterface) {
       return;
     }
 
-    this._checkForTTY();
+    this.#checkForTTY();
 
-    this._readlineInterface = readline.createInterface({ input: this.stdin });
+    this.#readlineInterface = readline.createInterface({ input: this.stdin });
 
     readline.emitKeypressEvents(process.stdin);
     this.stdin.setRawMode(true);
-    this.stdin.addListener('keypress', this._onKeypress);
+    this.stdin.addListener('keypress', this.#onKeypress);
   }
 
-  private _checkForTTY(): void {
+  #checkForTTY(): void {
     // Typescript thinks setRawMode always extists, but we're testing that assumption here.
     if (this.stdin.isTTY && (this.stdin as Partial<NodeJS.ReadStream>).setRawMode) {
       return;
@@ -83,63 +83,63 @@ export class KeyboardLoop {
     throw new AlreadyReportedError();
   }
 
-  private _uncaptureInput(): void {
-    if (!this._readlineInterface) {
+  #uncaptureInput(): void {
+    if (!this.#readlineInterface) {
       return;
     }
 
-    this.stdin.removeListener('keypress', this._onKeypress);
+    this.stdin.removeListener('keypress', this.#onKeypress);
     this.stdin.setRawMode(false);
-    this._readlineInterface.close();
-    this._readlineInterface = undefined;
+    this.#readlineInterface.close();
+    this.#readlineInterface = undefined;
   }
 
   protected hideCursor(): void {
-    if (this._cursorHidden) {
+    if (this.#cursorHidden) {
       return;
     }
-    this._cursorHidden = true;
+    this.#cursorHidden = true;
     this.stderr.write(ANSI_ESCAPE_SHOW_CURSOR);
   }
 
   protected unhideCursor(): void {
-    if (!this._cursorHidden) {
+    if (!this.#cursorHidden) {
       return;
     }
-    this._cursorHidden = false;
+    this.#cursorHidden = false;
     this.stderr.write(ANSI_ESCAPE_HIDE_CURSOR);
   }
 
   public async startAsync(): Promise<void> {
     try {
-      this._captureInput();
+      this.#captureInput();
       this.onStart();
       await new Promise<void>((resolve: () => void, reject: (error: Error) => void) => {
-        this._resolvePromise = resolve;
-        this._rejectPromise = reject;
+        this.#resolvePromise = resolve;
+        this.#rejectPromise = reject;
       });
     } finally {
-      this._uncaptureInput();
+      this.#uncaptureInput();
       this.unhideCursor();
     }
   }
 
   protected resolveAsync(): void {
-    if (!this._resolvePromise) {
+    if (!this.#resolvePromise) {
       return;
     }
-    this._resolvePromise();
-    this._resolvePromise = undefined;
-    this._rejectPromise = undefined;
+    this.#resolvePromise();
+    this.#resolvePromise = undefined;
+    this.#rejectPromise = undefined;
   }
 
   protected rejectAsync(error: Error): void {
-    if (!this._rejectPromise) {
+    if (!this.#rejectPromise) {
       return;
     }
-    this._rejectPromise(error);
-    this._resolvePromise = undefined;
-    this._rejectPromise = undefined;
+    this.#rejectPromise(error);
+    this.#resolvePromise = undefined;
+    this.#rejectPromise = undefined;
   }
 
   /** @virtual */
@@ -148,7 +148,7 @@ export class KeyboardLoop {
   /** @virtual */
   protected onKeypress(character: string, key: readline.Key): void {}
 
-  private _onKeypress = (character: string, key: readline.Key): void => {
+  #onKeypress = (character: string, key: readline.Key): void => {
     if (key.name === 'c' && key.ctrl && !key.meta && !key.shift) {
       // Intercept CTRL+C
       process.kill(process.pid, 'SIGINT');
diff --git a/libraries/rush-lib/src/logic/setup/SetupPackageRegistry.ts b/libraries/rush-lib/src/logic/setup/SetupPackageRegistry.ts
index 6ffa3504e6a..0ee3232f0c9 100644
--- a/libraries/rush-lib/src/logic/setup/SetupPackageRegistry.ts
+++ b/libraries/rush-lib/src/logic/setup/SetupPackageRegistry.ts
@@ -56,39 +56,39 @@ export interface ISetupPackageRegistryOptions {
 }
 
 export class SetupPackageRegistry {
-  private readonly _options: ISetupPackageRegistryOptions;
+  readonly #options: ISetupPackageRegistryOptions;
   public readonly rushConfiguration: RushConfiguration;
-  private readonly _terminal: Terminal;
-  private readonly _artifactoryConfiguration: ArtifactoryConfiguration;
-  private readonly _messages: IArtifactoryCustomizableMessages;
+  readonly #terminal: Terminal;
+  readonly #artifactoryConfiguration: ArtifactoryConfiguration;
+  readonly #messages: IArtifactoryCustomizableMessages;
 
   public constructor(options: ISetupPackageRegistryOptions) {
-    this._options = options;
+    this.#options = options;
     this.rushConfiguration = options.rushConfiguration;
 
-    this._terminal = new Terminal(
+    this.#terminal = new Terminal(
       new ConsoleTerminalProvider({
         verboseEnabled: options.isDebug
       })
     );
 
-    this._artifactoryConfiguration = new ArtifactoryConfiguration(
+    this.#artifactoryConfiguration = new ArtifactoryConfiguration(
       path.join(this.rushConfiguration.commonRushConfigFolder, 'artifactory.json')
     );
 
-    this._messages = {
+    this.#messages = {
       ...defaultMessages,
-      ...this._artifactoryConfiguration.configuration.packageRegistry.messageOverrides
+      ...this.#artifactoryConfiguration.configuration.packageRegistry.messageOverrides
     };
   }
 
-  private _writeInstructionBlock(message: string): void {
+  #writeInstructionBlock(message: string): void {
     if (message === '') {
       return;
     }
 
-    this._terminal.writeLine(PrintUtilities.wrapWords(message));
-    this._terminal.writeLine();
+    this.#terminal.writeLine(PrintUtilities.wrapWords(message));
+    this.#terminal.writeLine();
   }
 
   /**
@@ -98,9 +98,9 @@ export class SetupPackageRegistry {
    */
   public async checkOnlyAsync(): Promise<boolean> {
     const packageRegistry: IArtifactoryPackageRegistryJson =
-      this._artifactoryConfiguration.configuration.packageRegistry;
+      this.#artifactoryConfiguration.configuration.packageRegistry;
     if (!packageRegistry.enabled) {
-      this._terminal.writeVerbose('Skipping package registry setup because packageRegistry.enabled=false');
+      this.#terminal.writeVerbose('Skipping package registry setup because packageRegistry.enabled=false');
       return true;
     }
 
@@ -109,7 +109,7 @@ export class SetupPackageRegistry {
       throw new Error('The "registryUrl" setting in artifactory.json is missing or empty');
     }
 
-    if (!this._options.syncNpmrcAlreadyCalled) {
+    if (!this.#options.syncNpmrcAlreadyCalled) {
       Utilities.syncNpmrc({
         sourceNpmrcFolder: this.rushConfiguration.commonRushConfigFolder,
         targetNpmrcFolder: this.rushConfiguration.commonTempFolder,
@@ -128,7 +128,7 @@ export class SetupPackageRegistry {
       '--registry=' + packageRegistry.registryUrl
     ];
 
-    this._terminal.writeLine('Testing access to private NPM registry: ' + packageRegistry.registryUrl);
+    this.#terminal.writeLine('Testing access to private NPM registry: ' + packageRegistry.registryUrl);
 
     const result: child_process.SpawnSyncReturns<string> = Executable.spawnSync('npm', npmArgs, {
       currentWorkingDirectory: this.rushConfiguration.commonTempFolder,
@@ -136,7 +136,7 @@ export class SetupPackageRegistry {
       // Wait at most 10 seconds for "npm view" to succeed
       timeoutMs: 10 * 1000
     });
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
 
     // (This is not exactly correct, for example Node.js puts a string in error.errno instead of a string.)
     const error: (Error & Partial<NodeJS.ErrnoException>) | undefined = result.error;
@@ -168,30 +168,30 @@ export class SetupPackageRegistry {
     try {
       jsonOutput = JSON.parse(jsonContent);
     } catch (e) {
-      this._terminal.writeVerboseLine('NPM response:\n\n--------\n' + jsonContent + '\n--------\n\n');
+      this.#terminal.writeVerboseLine('NPM response:\n\n--------\n' + jsonContent + '\n--------\n\n');
       throw new InternalError('The "npm view" command returned an invalid JSON structure');
     }
 
     const errorCode: JsonObject = jsonOutput?.error?.code;
     if (typeof errorCode !== 'string') {
-      this._terminal.writeVerboseLine('NPM response:\n' + JSON.stringify(jsonOutput, undefined, 2) + '\n\n');
+      this.#terminal.writeVerboseLine('NPM response:\n' + JSON.stringify(jsonOutput, undefined, 2) + '\n\n');
       throw new InternalError('The "npm view" command returned unexpected output');
     }
 
     switch (errorCode) {
       case 'E404':
-        this._terminal.writeLine('NPM credentials are working');
-        this._terminal.writeLine();
+        this.#terminal.writeLine('NPM credentials are working');
+        this.#terminal.writeLine();
         return true;
       case 'E401':
       case 'E403':
-        this._terminal.writeVerboseLine(
+        this.#terminal.writeVerboseLine(
           'NPM response:\n' + JSON.stringify(jsonOutput, undefined, 2) + '\n\n'
         );
         // Credentials are missing or expired
         return false;
       default:
-        this._terminal.writeVerboseLine(
+        this.#terminal.writeVerboseLine(
           'NPM response:\n' + JSON.stringify(jsonOutput, undefined, 2) + '\n\n'
         );
         throw new Error(`The "npm view" command returned an unexpected error code "${errorCode}"`);
@@ -206,86 +206,86 @@ export class SetupPackageRegistry {
       return;
     }
 
-    this._terminal.writeWarningLine('NPM credentials are missing or expired');
-    this._terminal.writeLine();
+    this.#terminal.writeWarningLine('NPM credentials are missing or expired');
+    this.#terminal.writeLine();
 
     const packageRegistry: IArtifactoryPackageRegistryJson =
-      this._artifactoryConfiguration.configuration.packageRegistry;
+      this.#artifactoryConfiguration.configuration.packageRegistry;
 
     const fixThisProblem: boolean = await TerminalInput.promptYesNoAsync({
       message: 'Fix this problem now?',
       defaultValue: false
     });
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
     if (!fixThisProblem) {
       return;
     }
 
-    this._writeInstructionBlock(this._messages.introduction);
+    this.#writeInstructionBlock(this.#messages.introduction);
 
     const hasArtifactoryAccount: boolean = await TerminalInput.promptYesNoAsync({
       message: 'Do you already have an Artifactory user account?'
     });
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
 
     if (!hasArtifactoryAccount) {
-      this._writeInstructionBlock(this._messages.obtainAnAccount);
+      this.#writeInstructionBlock(this.#messages.obtainAnAccount);
       throw new AlreadyReportedError();
     }
 
-    if (this._messages.visitWebsite) {
-      this._writeInstructionBlock(this._messages.visitWebsite);
+    if (this.#messages.visitWebsite) {
+      this.#writeInstructionBlock(this.#messages.visitWebsite);
 
       const artifactoryWebsiteUrl: string =
-        this._artifactoryConfiguration.configuration.packageRegistry.artifactoryWebsiteUrl;
+        this.#artifactoryConfiguration.configuration.packageRegistry.artifactoryWebsiteUrl;
 
       if (artifactoryWebsiteUrl) {
-        this._terminal.writeLine('  ', Colorize.cyan(artifactoryWebsiteUrl));
-        this._terminal.writeLine();
+        this.#terminal.writeLine('  ', Colorize.cyan(artifactoryWebsiteUrl));
+        this.#terminal.writeLine();
       }
     }
 
-    this._writeInstructionBlock(this._messages.locateUserName);
+    this.#writeInstructionBlock(this.#messages.locateUserName);
 
     let artifactoryUser: string = await TerminalInput.promptLineAsync({
-      message: this._messages.userNamePrompt
+      message: this.#messages.userNamePrompt
     });
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
 
     artifactoryUser = artifactoryUser.trim();
     if (artifactoryUser.length === 0) {
-      this._terminal.writeLine(Colorize.red('Operation aborted because the input was empty'));
-      this._terminal.writeLine();
+      this.#terminal.writeLine(Colorize.red('Operation aborted because the input was empty'));
+      this.#terminal.writeLine();
       throw new AlreadyReportedError();
     }
 
-    this._writeInstructionBlock(this._messages.locateApiKey);
+    this.#writeInstructionBlock(this.#messages.locateApiKey);
 
     let artifactoryKey: string = await TerminalInput.promptPasswordLineAsync({
-      message: this._messages.apiKeyPrompt
+      message: this.#messages.apiKeyPrompt
     });
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
 
     artifactoryKey = artifactoryKey.trim();
     if (artifactoryKey.length === 0) {
-      this._terminal.writeLine(Colorize.red('Operation aborted because the input was empty'));
-      this._terminal.writeLine();
+      this.#terminal.writeLine(Colorize.red('Operation aborted because the input was empty'));
+      this.#terminal.writeLine();
       throw new AlreadyReportedError();
     }
 
-    await this._fetchTokenAndUpdateNpmrcAsync(artifactoryUser, artifactoryKey, packageRegistry);
+    await this.#fetchTokenAndUpdateNpmrcAsync(artifactoryUser, artifactoryKey, packageRegistry);
   }
 
   /**
    * Fetch a valid NPM token from the Artifactory service and add it to the `~/.npmrc` file,
    * preserving other settings in that file.
    */
-  private async _fetchTokenAndUpdateNpmrcAsync(
+  async #fetchTokenAndUpdateNpmrcAsync(
     artifactoryUser: string,
     artifactoryKey: string,
     packageRegistry: IArtifactoryPackageRegistryJson
   ): Promise<void> {
-    this._terminal.writeLine('\nFetching an NPM token from the Artifactory service...');
+    this.#terminal.writeLine('\nFetching an NPM token from the Artifactory service...');
 
     // Defer this import since it is conditionally needed.
     const { WebClient } = await import('../../utilities/WebClient');
@@ -356,7 +356,7 @@ export class SetupPackageRegistry {
 
     const npmrcPath: string = path.join(User.getHomeFolder(), '.npmrc');
 
-    this._mergeLinesIntoNpmrc(npmrcPath, linesToAdd);
+    this.#mergeLinesIntoNpmrc(npmrcPath, linesToAdd);
   }
 
   /**
@@ -373,7 +373,7 @@ export class SetupPackageRegistry {
    * - Under no circumstances is a duplicate key/value added to the file; in the case of
    *   duplicates, the earliest line in `linesToAdd` takes precedence
    */
-  private _mergeLinesIntoNpmrc(npmrcPath: string, linesToAdd: readonly string[]): void {
+  #mergeLinesIntoNpmrc(npmrcPath: string, linesToAdd: readonly string[]): void {
     // We'll replace entries with "undefined" if they get discarded
     const workingLinesToAdd: (string | undefined)[] = [...linesToAdd];
 
@@ -398,8 +398,8 @@ export class SetupPackageRegistry {
       }
     }
 
-    this._terminal.writeLine();
-    this._terminal.writeLine(Colorize.green('Adding Artifactory token to: '), npmrcPath);
+    this.#terminal.writeLine();
+    this.#terminal.writeLine(Colorize.green('Adding Artifactory token to: '), npmrcPath);
 
     const npmrcLines: string[] = [];
 
diff --git a/libraries/rush-lib/src/logic/setup/TerminalInput.ts b/libraries/rush-lib/src/logic/setup/TerminalInput.ts
index a73b4eda1f6..627dd7b9af9 100644
--- a/libraries/rush-lib/src/logic/setup/TerminalInput.ts
+++ b/libraries/rush-lib/src/logic/setup/TerminalInput.ts
@@ -82,23 +82,23 @@ class YesNoKeyboardLoop extends KeyboardLoop {
 }
 
 class PasswordKeyboardLoop extends KeyboardLoop {
-  private readonly _options: IPromptPasswordOptions;
-  private _passwordCharacter: string;
-  private _startX: number = 0;
-  private _printedY: number = 0;
-  private _lastPrintedLength: number = 0;
+  readonly #options: IPromptPasswordOptions;
+  #passwordCharacter: string;
+  #startX: number = 0;
+  #printedY: number = 0;
+  #lastPrintedLength: number = 0;
 
   public result: string = '';
 
   public constructor(options: IPromptPasswordOptions) {
     super();
-    this._options = options;
+    this.#options = options;
 
-    this._passwordCharacter =
-      this._options.passwordCharacter === undefined ? '*' : this._options.passwordCharacter.substr(0, 1);
+    this.#passwordCharacter =
+      this.#options.passwordCharacter === undefined ? '*' : this.#options.passwordCharacter.substr(0, 1);
   }
 
-  private _getLineWrapWidth(): number {
+  #getLineWrapWidth(): number {
     return this.stderr.columns ? this.stderr.columns : 80;
   }
 
@@ -107,7 +107,7 @@ class PasswordKeyboardLoop extends KeyboardLoop {
 
     readline.cursorTo(this.stderr, 0);
     readline.clearLine(this.stderr, 1);
-    const prefix: string = Colorize.green('==>') + ' ' + Colorize.bold(this._options.message) + ' ';
+    const prefix: string = Colorize.green('==>') + ' ' + Colorize.bold(this.#options.message) + ' ';
 
     this.stderr.write(prefix);
     let lineStartIndex: number = prefix.lastIndexOf('\n');
@@ -115,24 +115,24 @@ class PasswordKeyboardLoop extends KeyboardLoop {
       lineStartIndex = 0;
     }
     const line: string = prefix.substring(lineStartIndex);
-    this._startX = AnsiEscape.removeCodes(line).length % this._getLineWrapWidth();
+    this.#startX = AnsiEscape.removeCodes(line).length % this.#getLineWrapWidth();
   }
 
   protected override onKeypress(character: string, key: readline.Key): void {
     switch (key.name) {
       case 'enter':
       case 'return':
-        if (this._passwordCharacter !== '') {
+        if (this.#passwordCharacter !== '') {
           // To avoid disclosing the length of the password, after the user presses ENTER,
           // replace the "*********" sequence with exactly three stars ("***").
-          this._render(this._passwordCharacter.repeat(3));
+          this.#render(this.#passwordCharacter.repeat(3));
         }
         this.stderr.write('\n');
         this.resolveAsync();
         return;
       case 'backspace':
         this.result = this.result.substring(0, this.result.length - 1);
-        this._render(this.result);
+        this.#render(this.result);
         break;
       default:
         let printable: boolean = true;
@@ -146,50 +146,50 @@ class PasswordKeyboardLoop extends KeyboardLoop {
 
         if (printable) {
           this.result += character;
-          this._render(this.result);
+          this.#render(this.result);
         }
     }
   }
 
-  private _render(text: string): void {
+  #render(text: string): void {
     // Optimize rendering when we don't need to erase anything
-    const needsClear: boolean = text.length < this._lastPrintedLength;
-    this._lastPrintedLength = text.length;
+    const needsClear: boolean = text.length < this.#lastPrintedLength;
+    this.#lastPrintedLength = text.length;
 
     this.hideCursor();
 
     // Restore Y
-    while (this._printedY > 0) {
+    while (this.#printedY > 0) {
       readline.cursorTo(this.stderr, 0);
       if (needsClear) {
         readline.clearLine(this.stderr, 1);
       }
       readline.moveCursor(this.stderr, 0, -1);
-      --this._printedY;
+      --this.#printedY;
     }
 
     // Restore X
-    readline.cursorTo(this.stderr, this._startX);
+    readline.cursorTo(this.stderr, this.#startX);
 
     let i: number = 0;
-    let column: number = this._startX;
-    this._printedY = 0;
+    let column: number = this.#startX;
+    this.#printedY = 0;
     let buffer: string = '';
 
     while (i < text.length) {
-      if (this._passwordCharacter === '') {
+      if (this.#passwordCharacter === '') {
         buffer += text.substr(i, 1);
       } else {
-        buffer += this._passwordCharacter;
+        buffer += this.#passwordCharacter;
       }
 
       ++i;
       ++column;
 
       // -1 to avoid weird TTY behavior in final column
-      if (column >= this._getLineWrapWidth() - 1) {
+      if (column >= this.#getLineWrapWidth() - 1) {
         column = 0;
-        ++this._printedY;
+        ++this.#printedY;
         buffer += '\n';
       }
     }
diff --git a/libraries/rush-lib/src/logic/test/Telemetry.test.ts b/libraries/rush-lib/src/logic/test/Telemetry.test.ts
index aebc60ef4a9..a1e4511b0e2 100644
--- a/libraries/rush-lib/src/logic/test/Telemetry.test.ts
+++ b/libraries/rush-lib/src/logic/test/Telemetry.test.ts
@@ -10,7 +10,7 @@ import { Telemetry, type ITelemetryData, type ITelemetryMachineInfo } from '../T
 import { RushSession } from '../../pluginFramework/RushSession';
 
 interface ITelemetryPrivateMembers extends Omit<Telemetry, '_flushAsyncTasks'> {
-  _flushAsyncTasks: Map<symbol, Promise<void>>;
+  _flushAsyncTasks: Set<Promise<void>>;
 }
 
 describe(Telemetry.name, () => {
diff --git a/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinder.ts b/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinder.ts
index f456dd81d99..719924aae70 100644
--- a/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinder.ts
+++ b/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinder.ts
@@ -52,18 +52,18 @@ export class VersionMismatchFinder {
    *   }
    * }
    */
-  private _allowedAlternativeVersion: Map<string, ReadonlyArray<string>>;
-  private _mismatches: Map<string, Map<string, VersionMismatchFinderEntity[]>>;
-  private _projects: VersionMismatchFinderEntity[];
+  #allowedAlternativeVersion: Map<string, ReadonlyArray<string>>;
+  #mismatches: Map<string, Map<string, VersionMismatchFinderEntity[]>>;
+  #projects: VersionMismatchFinderEntity[];
 
   public constructor(
     projects: VersionMismatchFinderEntity[],
     allowedAlternativeVersions?: Map<string, ReadonlyArray<string>>
   ) {
-    this._projects = projects;
-    this._mismatches = new Map<string, Map<string, VersionMismatchFinderEntity[]>>();
-    this._allowedAlternativeVersion = allowedAlternativeVersions || new Map<string, ReadonlyArray<string>>();
-    this._analyze();
+    this.#projects = projects;
+    this.#mismatches = new Map<string, Map<string, VersionMismatchFinderEntity[]>>();
+    this.#allowedAlternativeVersion = allowedAlternativeVersions || new Map<string, ReadonlyArray<string>>();
+    this.#analyze();
   }
 
   public static rushCheck(
@@ -130,19 +130,19 @@ export class VersionMismatchFinder {
   }
 
   public get mismatches(): ReadonlyMap<string, ReadonlyMap<string, readonly VersionMismatchFinderEntity[]>> {
-    return this._mismatches;
+    return this.#mismatches;
   }
 
   public get numberOfMismatches(): number {
-    return this._mismatches.size;
+    return this.#mismatches.size;
   }
 
   public getMismatches(): string[] {
-    return this._getKeys(this._mismatches);
+    return this.#getKeys(this.#mismatches);
   }
 
   public getVersionsOfMismatch(mismatch: string): string[] | undefined {
-    return this._mismatches.has(mismatch) ? this._getKeys(this._mismatches.get(mismatch)) : undefined;
+    return this.#mismatches.has(mismatch) ? this.#getKeys(this.#mismatches.get(mismatch)) : undefined;
   }
 
   public getConsumersOfMismatch(
@@ -150,7 +150,7 @@ export class VersionMismatchFinder {
     version: string
   ): VersionMismatchFinderEntity[] | undefined {
     const mismatchedPackage: Map<string, VersionMismatchFinderEntity[]> | undefined =
-      this._mismatches.get(mismatch);
+      this.#mismatches.get(mismatch);
     if (!mismatchedPackage) {
       return undefined;
     }
@@ -228,8 +228,8 @@ export class VersionMismatchFinder {
     });
   }
 
-  private _analyze(): void {
-    this._projects.forEach((project: VersionMismatchFinderEntity) => {
+  #analyze(): void {
+    this.#projects.forEach((project: VersionMismatchFinderEntity) => {
       if (!project.skipRushCheck) {
         // NOTE: We do not consider peer dependencies here.  The purpose of "rush check" is
         // mainly to avoid side-by-side duplicates in the node_modules folder, whereas
@@ -244,16 +244,16 @@ export class VersionMismatchFinder {
 
             const isCyclic: boolean = project.decoupledLocalDependencies.has(dependency.name);
 
-            if (this._isVersionAllowedAlternative(dependency.name, version)) {
+            if (this.#isVersionAllowedAlternative(dependency.name, version)) {
               return;
             }
 
             const name: string = dependency.name + (isCyclic ? ' (cyclic)' : '');
 
             let dependencyVersions: Map<string, VersionMismatchFinderEntity[]> | undefined =
-              this._mismatches.get(name);
+              this.#mismatches.get(name);
             if (!dependencyVersions) {
-              this._mismatches.set(
+              this.#mismatches.set(
                 name,
                 (dependencyVersions = new Map<string, VersionMismatchFinderEntity[]>())
               );
@@ -270,21 +270,21 @@ export class VersionMismatchFinder {
       }
     });
 
-    this._mismatches.forEach((mismatches: Map<string, VersionMismatchFinderEntity[]>, project: string) => {
+    this.#mismatches.forEach((mismatches: Map<string, VersionMismatchFinderEntity[]>, project: string) => {
       if (mismatches.size <= 1) {
-        this._mismatches.delete(project);
+        this.#mismatches.delete(project);
       }
     });
   }
 
-  private _isVersionAllowedAlternative(dependency: string, version: string): boolean {
+  #isVersionAllowedAlternative(dependency: string, version: string): boolean {
     const allowedAlternatives: ReadonlyArray<string> | undefined =
-      this._allowedAlternativeVersion.get(dependency);
+      this.#allowedAlternativeVersion.get(dependency);
     return Boolean(allowedAlternatives && allowedAlternatives.indexOf(version) > -1);
   }
 
   // eslint-disable-next-line @typescript-eslint/no-explicit-any
-  private _getKeys(iterable: Map<string, any> | undefined): string[] {
+  #getKeys(iterable: Map<string, any> | undefined): string[] {
     const keys: string[] = [];
     if (iterable) {
       // eslint-disable-next-line @typescript-eslint/no-explicit-any
diff --git a/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinderCommonVersions.ts b/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinderCommonVersions.ts
index 1e2c11b17bf..a571a140bc3 100644
--- a/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinderCommonVersions.ts
+++ b/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinderCommonVersions.ts
@@ -7,7 +7,7 @@ import type { CommonVersionsConfiguration } from '../../api/CommonVersionsConfig
 import { VersionMismatchFinderEntity } from './VersionMismatchFinderEntity';
 
 export class VersionMismatchFinderCommonVersions extends VersionMismatchFinderEntity {
-  private _fileManager: CommonVersionsConfiguration;
+  #fileManager: CommonVersionsConfiguration;
 
   public constructor(commonVersionsConfiguration: CommonVersionsConfiguration) {
     super({
@@ -15,29 +15,29 @@ export class VersionMismatchFinderCommonVersions extends VersionMismatchFinderEn
       decoupledLocalDependencies: new Set<string>()
     });
 
-    this._fileManager = commonVersionsConfiguration;
+    this.#fileManager = commonVersionsConfiguration;
   }
 
   public get filePath(): string {
-    return this._fileManager.filePath;
+    return this.#fileManager.filePath;
   }
 
   public get allDependencies(): ReadonlyArray<PackageJsonDependency> {
     const dependencies: PackageJsonDependency[] = [];
 
-    this._fileManager.getAllPreferredVersions().forEach((version, dependencyName) => {
-      dependencies.push(this._getPackageJsonDependency(dependencyName, version));
+    this.#fileManager.getAllPreferredVersions().forEach((version, dependencyName) => {
+      dependencies.push(this.#getPackageJsonDependency(dependencyName, version));
     });
 
     return dependencies;
   }
 
   public tryGetDependency(packageName: string): PackageJsonDependency | undefined {
-    const version: string | undefined = this._fileManager.getAllPreferredVersions().get(packageName);
+    const version: string | undefined = this.#fileManager.getAllPreferredVersions().get(packageName);
     if (!version) {
       return undefined;
     } else {
-      return this._getPackageJsonDependency(packageName, version);
+      return this.#getPackageJsonDependency(packageName, version);
     }
   }
 
@@ -56,7 +56,7 @@ export class VersionMismatchFinderCommonVersions extends VersionMismatchFinderEn
       );
     }
 
-    this._fileManager.preferredVersions.set(packageName, newVersion);
+    this.#fileManager.preferredVersions.set(packageName, newVersion);
   }
 
   public removeDependency(packageName: string): void {
@@ -64,10 +64,10 @@ export class VersionMismatchFinderCommonVersions extends VersionMismatchFinderEn
   }
 
   public async saveIfModifiedAsync(): Promise<boolean> {
-    return await this._fileManager.saveAsync();
+    return await this.#fileManager.saveAsync();
   }
 
-  private _getPackageJsonDependency(dependencyName: string, version: string): PackageJsonDependency {
+  #getPackageJsonDependency(dependencyName: string, version: string): PackageJsonDependency {
     return new PackageJsonDependency(dependencyName, version, DependencyType.Regular, () =>
       this.addOrUpdateDependency(dependencyName, version, DependencyType.Regular)
     );
diff --git a/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinderProject.ts b/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinderProject.ts
index cc63370b687..78effefc747 100644
--- a/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinderProject.ts
+++ b/libraries/rush-lib/src/logic/versionMismatch/VersionMismatchFinderProject.ts
@@ -7,7 +7,7 @@ import type { RushConfigurationProject } from '../../api/RushConfigurationProjec
 
 export class VersionMismatchFinderProject extends VersionMismatchFinderEntity {
   public packageName: string;
-  private _fileManager: PackageJsonEditor;
+  #fileManager: PackageJsonEditor;
 
   public constructor(project: RushConfigurationProject) {
     super({
@@ -16,24 +16,24 @@ export class VersionMismatchFinderProject extends VersionMismatchFinderEntity {
       skipRushCheck: project.skipRushCheck
     });
 
-    this._fileManager = project.packageJsonEditor;
+    this.#fileManager = project.packageJsonEditor;
     this.packageName = project.packageName;
   }
 
   public get filePath(): string {
-    return this._fileManager.filePath;
+    return this.#fileManager.filePath;
   }
 
   public get allDependencies(): ReadonlyArray<PackageJsonDependency> {
-    return [...this._fileManager.dependencyList, ...this._fileManager.devDependencyList];
+    return [...this.#fileManager.dependencyList, ...this.#fileManager.devDependencyList];
   }
 
   public tryGetDependency(packageName: string): PackageJsonDependency | undefined {
-    return this._fileManager.tryGetDependency(packageName);
+    return this.#fileManager.tryGetDependency(packageName);
   }
 
   public tryGetDevDependency(packageName: string): PackageJsonDependency | undefined {
-    return this._fileManager.tryGetDevDependency(packageName);
+    return this.#fileManager.tryGetDevDependency(packageName);
   }
 
   public addOrUpdateDependency(
@@ -41,14 +41,14 @@ export class VersionMismatchFinderProject extends VersionMismatchFinderEntity {
     newVersion: string,
     dependencyType: DependencyType
   ): void {
-    return this._fileManager.addOrUpdateDependency(packageName, newVersion, dependencyType);
+    return this.#fileManager.addOrUpdateDependency(packageName, newVersion, dependencyType);
   }
 
   public removeDependency(packageName: string, dependencyType: DependencyType): void {
-    return this._fileManager.removeDependency(packageName, dependencyType);
+    return this.#fileManager.removeDependency(packageName, dependencyType);
   }
 
   public async saveIfModifiedAsync(): Promise<boolean> {
-    return await this._fileManager.saveIfModifiedAsync();
+    return await this.#fileManager.saveIfModifiedAsync();
   }
 }
diff --git a/libraries/rush-lib/src/logic/yarn/YarnShrinkwrapFile.ts b/libraries/rush-lib/src/logic/yarn/YarnShrinkwrapFile.ts
index 920c72df3d4..5534ee6c1b4 100644
--- a/libraries/rush-lib/src/logic/yarn/YarnShrinkwrapFile.ts
+++ b/libraries/rush-lib/src/logic/yarn/YarnShrinkwrapFile.ts
@@ -107,17 +107,17 @@ const _packageNameAndSemVerRegExp: RegExp = /^(@?[^@\s]+)(?:@(.*))?$/;
 export class YarnShrinkwrapFile extends BaseShrinkwrapFile {
   public readonly isWorkspaceCompatible: boolean;
 
-  private _shrinkwrapJson: IYarnShrinkwrapJson;
-  private _tempProjectNames: string[];
+  #shrinkwrapJson: IYarnShrinkwrapJson;
+  #tempProjectNames: string[];
 
   private constructor(shrinkwrapJson: IYarnShrinkwrapJson) {
     super();
-    this._shrinkwrapJson = shrinkwrapJson;
-    this._tempProjectNames = [];
+    this.#shrinkwrapJson = shrinkwrapJson;
+    this.#tempProjectNames = [];
 
     const seenEntries: Set<string> = new Set();
 
-    for (const key of Object.keys(this._shrinkwrapJson)) {
+    for (const key of Object.keys(this.#shrinkwrapJson)) {
       // Example key:
       const packageNameAndSemVer: IPackageNameAndSemVer = _decodePackageNameAndSemVer(key);
 
@@ -143,9 +143,9 @@ export class YarnShrinkwrapFile extends BaseShrinkwrapFile {
           );
         }
 
-        this._tempProjectNames.push(packageNameAndSemVer.packageName);
+        this.#tempProjectNames.push(packageNameAndSemVer.packageName);
 
-        const entry: IYarnShrinkwrapEntry = this._shrinkwrapJson[key];
+        const entry: IYarnShrinkwrapEntry = this.#shrinkwrapJson[key];
 
         // Yarn fails installation if the integrity hash does not match a "file://" reference to a tarball.
         // This is incorrect:  Normally a mismatched integrity hash does indicate a corrupted download,
@@ -165,7 +165,7 @@ export class YarnShrinkwrapFile extends BaseShrinkwrapFile {
       }
     }
 
-    this._tempProjectNames.sort(); // make the result deterministic
+    this.#tempProjectNames.sort(); // make the result deterministic
 
     // We don't support Yarn workspaces yet
     this.isWorkspaceCompatible = false;
@@ -189,7 +189,7 @@ export class YarnShrinkwrapFile extends BaseShrinkwrapFile {
   }
 
   public override getTempProjectNames(): ReadonlyArray<string> {
-    return this._tempProjectNames;
+    return this.#tempProjectNames;
   }
 
   public override hasCompatibleTopLevelDependency(dependencySpecifier: DependencySpecifier): boolean {
@@ -201,7 +201,7 @@ export class YarnShrinkwrapFile extends BaseShrinkwrapFile {
     });
 
     // Check whether this exact key appears in the shrinkwrap file
-    return Object.hasOwnProperty.call(this._shrinkwrapJson, key);
+    return Object.hasOwnProperty.call(this.#shrinkwrapJson, key);
   }
 
   public override tryEnsureCompatibleDependency(
@@ -212,7 +212,7 @@ export class YarnShrinkwrapFile extends BaseShrinkwrapFile {
   }
 
   protected override serialize(): string {
-    return lockfileModule.stringify(this._shrinkwrapJson);
+    return lockfileModule.stringify(this.#shrinkwrapJson);
   }
 
   protected override getTopLevelDependencyVersion(dependencyName: string): DependencySpecifier | undefined {
diff --git a/libraries/rush-lib/src/pluginFramework/PluginLoader/PluginLoaderBase.ts b/libraries/rush-lib/src/pluginFramework/PluginLoader/PluginLoaderBase.ts
index 1c56731bdbe..a437a107e15 100644
--- a/libraries/rush-lib/src/pluginFramework/PluginLoader/PluginLoaderBase.ts
+++ b/libraries/rush-lib/src/pluginFramework/PluginLoader/PluginLoaderBase.ts
@@ -68,7 +68,7 @@ export abstract class PluginLoaderBase<
   }
 
   public load(): IRushPlugin | undefined {
-    const resolvedPluginPath: string | undefined = this._resolvePlugin();
+    const resolvedPluginPath: string | undefined = this.#resolvePlugin();
     if (!resolvedPluginPath) {
       return undefined;
     }
@@ -76,11 +76,11 @@ export abstract class PluginLoaderBase<
 
     RushSdk.ensureInitialized();
 
-    return this._loadAndValidatePluginPackage(resolvedPluginPath, pluginOptions);
+    return this.#loadAndValidatePluginPackage(resolvedPluginPath, pluginOptions);
   }
 
   public get pluginManifest(): IRushPluginManifest {
-    return this._getRushPluginManifest();
+    return this.#getRushPluginManifest();
   }
 
   public getCommandLineConfiguration(): CommandLineConfiguration | undefined {
@@ -113,14 +113,14 @@ export abstract class PluginLoaderBase<
   }
 
   protected _getCommandLineJsonFilePath(): string | undefined {
-    const { commandLineJsonFilePath } = this._getRushPluginManifest();
+    const { commandLineJsonFilePath } = this.#getRushPluginManifest();
     if (!commandLineJsonFilePath) {
       return undefined;
     }
     return path.join(this.packageFolder, commandLineJsonFilePath);
   }
 
-  private _loadAndValidatePluginPackage(resolvedPluginPath: string, options?: JsonObject): IRushPlugin {
+  #loadAndValidatePluginPackage(resolvedPluginPath: string, options?: JsonObject): IRushPlugin {
     type IRushPluginCtor<T = JsonObject> = new (opts: T) => IRushPlugin;
     let pluginPackage: IRushPluginCtor;
     try {
@@ -148,8 +148,8 @@ export abstract class PluginLoaderBase<
     return plugin;
   }
 
-  private _resolvePlugin(): string | undefined {
-    const entryPoint: string | undefined = this._getRushPluginManifest().entryPoint;
+  #resolvePlugin(): string | undefined {
+    const entryPoint: string | undefined = this.#getRushPluginManifest().entryPoint;
     if (!entryPoint) {
       return undefined;
     }
@@ -189,7 +189,7 @@ export abstract class PluginLoaderBase<
   }
 
   protected _getRushPluginOptionsSchema(): JsonSchema | undefined {
-    const optionsSchema: string | undefined = this._getRushPluginManifest().optionsSchema;
+    const optionsSchema: string | undefined = this.#getRushPluginManifest().optionsSchema;
     if (!optionsSchema) {
       return undefined;
     }
@@ -197,7 +197,7 @@ export abstract class PluginLoaderBase<
     return JsonSchema.fromFile(optionsSchemaFilePath);
   }
 
-  private _getRushPluginManifest(): IRushPluginManifest {
+  #getRushPluginManifest(): IRushPluginManifest {
     if (!this._manifestCache) {
       const packageName: string = this.packageName;
       const pluginName: string = this.pluginName;
diff --git a/libraries/rush-lib/src/pluginFramework/PluginManager.ts b/libraries/rush-lib/src/pluginFramework/PluginManager.ts
index 9a5181e078c..926aac1a5e8 100644
--- a/libraries/rush-lib/src/pluginFramework/PluginManager.ts
+++ b/libraries/rush-lib/src/pluginFramework/PluginManager.ts
@@ -29,26 +29,26 @@ export interface ICustomCommandLineConfigurationInfo {
 }
 
 export class PluginManager {
-  private readonly _terminal: ITerminal;
-  private readonly _rushConfiguration: RushConfiguration;
-  private readonly _rushSession: RushSession;
-  private readonly _restrictConsoleOutput: boolean;
-  private readonly _builtInPluginLoaders: BuiltInPluginLoader[];
-  private readonly _autoinstallerPluginLoaders: AutoinstallerPluginLoader[];
-  private readonly _installedAutoinstallerNames: Set<string>;
-  private readonly _loadedPluginNames: Set<string> = new Set<string>();
-  private readonly _rushGlobalFolder: RushGlobalFolder;
-
-  private _error: Error | undefined;
+  readonly #terminal: ITerminal;
+  readonly #rushConfiguration: RushConfiguration;
+  readonly #rushSession: RushSession;
+  readonly #restrictConsoleOutput: boolean;
+  readonly #builtInPluginLoaders: BuiltInPluginLoader[];
+  readonly #autoinstallerPluginLoaders: AutoinstallerPluginLoader[];
+  readonly #installedAutoinstallerNames: Set<string>;
+  readonly #loadedPluginNames: Set<string> = new Set<string>();
+  readonly #rushGlobalFolder: RushGlobalFolder;
+
+  #error: Error | undefined;
 
   public constructor(options: IPluginManagerOptions) {
-    this._terminal = options.terminal;
-    this._rushConfiguration = options.rushConfiguration;
-    this._rushSession = options.rushSession;
-    this._restrictConsoleOutput = options.restrictConsoleOutput;
-    this._rushGlobalFolder = options.rushGlobalFolder;
+    this.#terminal = options.terminal;
+    this.#rushConfiguration = options.rushConfiguration;
+    this.#rushSession = options.rushSession;
+    this.#restrictConsoleOutput = options.restrictConsoleOutput;
+    this.#rushGlobalFolder = options.rushGlobalFolder;
 
-    this._installedAutoinstallerNames = new Set<string>();
+    this.#installedAutoinstallerNames = new Set<string>();
 
     // Eventually we will require end users to explicitly configure all Rush plugins in use, regardless of
     // whether they are first party or third party plugins.  However, we're postponing that requirement
@@ -89,23 +89,23 @@ export class PluginManager {
       '@rushstack/rush-azure-storage-build-cache-plugin'
     );
 
-    this._builtInPluginLoaders = builtInPluginConfigurations.map((pluginConfiguration) => {
+    this.#builtInPluginLoaders = builtInPluginConfigurations.map((pluginConfiguration) => {
       return new BuiltInPluginLoader({
         pluginConfiguration,
-        rushConfiguration: this._rushConfiguration,
-        terminal: this._terminal
+        rushConfiguration: this.#rushConfiguration,
+        terminal: this.#terminal
       });
     });
 
-    this._autoinstallerPluginLoaders = (
-      this._rushConfiguration?._rushPluginsConfiguration.configuration.plugins ?? []
+    this.#autoinstallerPluginLoaders = (
+      this.#rushConfiguration?._rushPluginsConfiguration.configuration.plugins ?? []
     ).map((pluginConfiguration) => {
       return new AutoinstallerPluginLoader({
         pluginConfiguration,
-        rushConfiguration: this._rushConfiguration,
-        terminal: this._terminal,
-        restrictConsoleOutput: this._restrictConsoleOutput,
-        rushGlobalFolder: this._rushGlobalFolder
+        rushConfiguration: this.#rushConfiguration,
+        terminal: this.#terminal,
+        restrictConsoleOutput: this.#restrictConsoleOutput,
+        rushGlobalFolder: this.#rushGlobalFolder
       });
     });
   }
@@ -116,74 +116,74 @@ export class PluginManager {
    * (unless we are invoking a command that is used to fix plugin problems).
    */
   public get error(): Error | undefined {
-    return this._error;
+    return this.#error;
   }
 
   public async updateAsync(): Promise<void> {
-    await this._preparePluginAutoinstallersAsync(this._autoinstallerPluginLoaders);
+    await this._preparePluginAutoinstallersAsync(this.#autoinstallerPluginLoaders);
     const preparedAutoinstallerNames: Set<string> = new Set<string>();
-    for (const { autoinstaller } of this._autoinstallerPluginLoaders) {
+    for (const { autoinstaller } of this.#autoinstallerPluginLoaders) {
       const storePath: string = AutoinstallerPluginLoader.getPluginAutoinstallerStorePath(autoinstaller);
       if (!preparedAutoinstallerNames.has(autoinstaller.name)) {
         FileSystem.ensureEmptyFolder(storePath);
         preparedAutoinstallerNames.add(autoinstaller.name);
       }
     }
-    for (const pluginLoader of this._autoinstallerPluginLoaders) {
+    for (const pluginLoader of this.#autoinstallerPluginLoaders) {
       pluginLoader.update();
     }
   }
 
   public async reinitializeAllPluginsForCommandAsync(commandName: string): Promise<void> {
-    this._error = undefined;
+    this.#error = undefined;
     await this.tryInitializeUnassociatedPluginsAsync();
     await this.tryInitializeAssociatedCommandPluginsAsync(commandName);
   }
 
   public async _preparePluginAutoinstallersAsync(pluginLoaders: AutoinstallerPluginLoader[]): Promise<void> {
     for (const { autoinstaller } of pluginLoaders) {
-      if (!this._installedAutoinstallerNames.has(autoinstaller.name)) {
+      if (!this.#installedAutoinstallerNames.has(autoinstaller.name)) {
         await autoinstaller.prepareAsync();
-        this._installedAutoinstallerNames.add(autoinstaller.name);
+        this.#installedAutoinstallerNames.add(autoinstaller.name);
       }
     }
   }
 
   public async tryInitializeUnassociatedPluginsAsync(): Promise<void> {
     try {
-      const autoinstallerPluginLoaders: AutoinstallerPluginLoader[] = this._getUnassociatedPluginLoaders(
-        this._autoinstallerPluginLoaders
+      const autoinstallerPluginLoaders: AutoinstallerPluginLoader[] = this.#getUnassociatedPluginLoaders(
+        this.#autoinstallerPluginLoaders
       );
       await this._preparePluginAutoinstallersAsync(autoinstallerPluginLoaders);
-      const builtInPluginLoaders: BuiltInPluginLoader[] = this._getUnassociatedPluginLoaders(
-        this._builtInPluginLoaders
+      const builtInPluginLoaders: BuiltInPluginLoader[] = this.#getUnassociatedPluginLoaders(
+        this.#builtInPluginLoaders
       );
-      this._initializePlugins([...builtInPluginLoaders, ...autoinstallerPluginLoaders]);
+      this.#initializePlugins([...builtInPluginLoaders, ...autoinstallerPluginLoaders]);
     } catch (e) {
-      this._error = e as Error;
+      this.#error = e as Error;
     }
   }
 
   public async tryInitializeAssociatedCommandPluginsAsync(commandName: string): Promise<void> {
     try {
-      const autoinstallerPluginLoaders: AutoinstallerPluginLoader[] = this._getPluginLoadersForCommand(
+      const autoinstallerPluginLoaders: AutoinstallerPluginLoader[] = this.#getPluginLoadersForCommand(
         commandName,
-        this._autoinstallerPluginLoaders
+        this.#autoinstallerPluginLoaders
       );
       await this._preparePluginAutoinstallersAsync(autoinstallerPluginLoaders);
-      const builtInPluginLoaders: BuiltInPluginLoader[] = this._getPluginLoadersForCommand(
+      const builtInPluginLoaders: BuiltInPluginLoader[] = this.#getPluginLoadersForCommand(
         commandName,
-        this._builtInPluginLoaders
+        this.#builtInPluginLoaders
       );
-      this._initializePlugins([...builtInPluginLoaders, ...autoinstallerPluginLoaders]);
+      this.#initializePlugins([...builtInPluginLoaders, ...autoinstallerPluginLoaders]);
     } catch (e) {
-      this._error = e as Error;
+      this.#error = e as Error;
     }
   }
 
   public tryGetCustomCommandLineConfigurationInfos(): ICustomCommandLineConfigurationInfo[] {
     const commandLineConfigurationInfos: ICustomCommandLineConfigurationInfo[] = [];
-    for (const pluginLoader of this._autoinstallerPluginLoaders) {
+    for (const pluginLoader of this.#autoinstallerPluginLoaders) {
       const commandLineConfiguration: CommandLineConfiguration | undefined =
         pluginLoader.getCommandLineConfiguration();
       if (commandLineConfiguration) {
@@ -196,21 +196,21 @@ export class PluginManager {
     return commandLineConfigurationInfos;
   }
 
-  private _initializePlugins(pluginLoaders: PluginLoaderBase[]): void {
+  #initializePlugins(pluginLoaders: PluginLoaderBase[]): void {
     for (const pluginLoader of pluginLoaders) {
       const pluginName: string = pluginLoader.pluginName;
-      if (this._loadedPluginNames.has(pluginName)) {
+      if (this.#loadedPluginNames.has(pluginName)) {
         throw new Error(`Error applying plugin: A plugin with name "${pluginName}" has already been applied`);
       }
       const plugin: IRushPlugin | undefined = pluginLoader.load();
-      this._loadedPluginNames.add(pluginName);
+      this.#loadedPluginNames.add(pluginName);
       if (plugin) {
-        this._applyPlugin(plugin, pluginName);
+        this.#applyPlugin(plugin, pluginName);
       }
     }
   }
 
-  private _getUnassociatedPluginLoaders<T extends AutoinstallerPluginLoader | BuiltInPluginLoader>(
+  #getUnassociatedPluginLoaders<T extends AutoinstallerPluginLoader | BuiltInPluginLoader>(
     pluginLoaders: T[]
   ): T[] {
     return pluginLoaders.filter((pluginLoader) => {
@@ -218,7 +218,7 @@ export class PluginManager {
     });
   }
 
-  private _getPluginLoadersForCommand<T extends AutoinstallerPluginLoader | BuiltInPluginLoader>(
+  #getPluginLoadersForCommand<T extends AutoinstallerPluginLoader | BuiltInPluginLoader>(
     commandName: string,
     pluginLoaders: T[]
   ): T[] {
@@ -227,9 +227,9 @@ export class PluginManager {
     });
   }
 
-  private _applyPlugin(plugin: IRushPlugin, pluginName: string): void {
+  #applyPlugin(plugin: IRushPlugin, pluginName: string): void {
     try {
-      plugin.apply(this._rushSession, this._rushConfiguration);
+      plugin.apply(this.#rushSession, this.#rushConfiguration);
     } catch (e) {
       throw new InternalError(`Error applying "${pluginName}": ${e}`);
     }
diff --git a/libraries/rush-lib/src/pluginFramework/RushSession.ts b/libraries/rush-lib/src/pluginFramework/RushSession.ts
index 0e512764438..2d0e5585b35 100644
--- a/libraries/rush-lib/src/pluginFramework/RushSession.ts
+++ b/libraries/rush-lib/src/pluginFramework/RushSession.ts
@@ -37,14 +37,14 @@ export type CobuildLockProviderFactory = (
  * @beta
  */
 export class RushSession {
-  private readonly _options: IRushSessionOptions;
-  private readonly _cloudBuildCacheProviderFactories: Map<string, CloudBuildCacheProviderFactory> = new Map();
-  private readonly _cobuildLockProviderFactories: Map<string, CobuildLockProviderFactory> = new Map();
+  readonly #options: IRushSessionOptions;
+  readonly #cloudBuildCacheProviderFactories: Map<string, CloudBuildCacheProviderFactory> = new Map();
+  readonly #cobuildLockProviderFactories: Map<string, CobuildLockProviderFactory> = new Map();
 
   public readonly hooks: RushLifecycleHooks;
 
   public constructor(options: IRushSessionOptions) {
-    this._options = options;
+    this.#options = options;
 
     this.hooks = new RushLifecycleHooks();
   }
@@ -54,51 +54,51 @@ export class RushSession {
       throw new InternalError('RushSession.getLogger(name) called without a name');
     }
 
-    const terminalProvider: ITerminalProvider = this._options.terminalProvider;
+    const terminalProvider: ITerminalProvider = this.#options.terminalProvider;
     const loggerOptions: ILoggerOptions = {
       loggerName: name,
-      getShouldPrintStacks: () => this._options.getIsDebugMode(),
+      getShouldPrintStacks: () => this.#options.getIsDebugMode(),
       terminalProvider
     };
     return new Logger(loggerOptions);
   }
 
   public get terminalProvider(): ITerminalProvider {
-    return this._options.terminalProvider;
+    return this.#options.terminalProvider;
   }
 
   public registerCloudBuildCacheProviderFactory(
     cacheProviderName: string,
     factory: CloudBuildCacheProviderFactory
   ): void {
-    if (this._cloudBuildCacheProviderFactories.has(cacheProviderName)) {
+    if (this.#cloudBuildCacheProviderFactories.has(cacheProviderName)) {
       throw new Error(`A build cache provider factory for ${cacheProviderName} has already been registered`);
     }
 
-    this._cloudBuildCacheProviderFactories.set(cacheProviderName, factory);
+    this.#cloudBuildCacheProviderFactories.set(cacheProviderName, factory);
   }
 
   public getCloudBuildCacheProviderFactory(
     cacheProviderName: string
   ): CloudBuildCacheProviderFactory | undefined {
-    return this._cloudBuildCacheProviderFactories.get(cacheProviderName);
+    return this.#cloudBuildCacheProviderFactories.get(cacheProviderName);
   }
 
   public registerCobuildLockProviderFactory(
     cobuildLockProviderName: string,
     factory: CobuildLockProviderFactory
   ): void {
-    if (this._cobuildLockProviderFactories.has(cobuildLockProviderName)) {
+    if (this.#cobuildLockProviderFactories.has(cobuildLockProviderName)) {
       throw new Error(
         `A cobuild lock provider factory for ${cobuildLockProviderName} has already been registered`
       );
     }
-    this._cobuildLockProviderFactories.set(cobuildLockProviderName, factory);
+    this.#cobuildLockProviderFactories.set(cobuildLockProviderName, factory);
   }
 
   public getCobuildLockProviderFactory(
     cobuildLockProviderName: string
   ): CobuildLockProviderFactory | undefined {
-    return this._cobuildLockProviderFactories.get(cobuildLockProviderName);
+    return this.#cobuildLockProviderFactories.get(cobuildLockProviderName);
   }
 }
diff --git a/libraries/rush-lib/src/pluginFramework/logging/Logger.ts b/libraries/rush-lib/src/pluginFramework/logging/Logger.ts
index 46b01be524f..389453d6a42 100644
--- a/libraries/rush-lib/src/pluginFramework/logging/Logger.ts
+++ b/libraries/rush-lib/src/pluginFramework/logging/Logger.ts
@@ -27,14 +27,14 @@ export interface ILoggerOptions {
 }
 
 export class Logger implements ILogger {
-  private readonly _options: ILoggerOptions;
-  private readonly _errors: Error[] = [];
-  private readonly _warnings: Error[] = [];
+  readonly #options: ILoggerOptions;
+  readonly #errors: Error[] = [];
+  readonly #warnings: Error[] = [];
 
   public readonly terminal: Terminal;
 
   public constructor(options: ILoggerOptions) {
-    this._options = options;
+    this.#options = options;
     this.terminal = new Terminal(options.terminalProvider);
   }
 
@@ -54,9 +54,9 @@ export class Logger implements ILogger {
    * {@inheritdoc ILogger.emitError}
    */
   public emitError(error: Error): void {
-    this._errors.push(error);
+    this.#errors.push(error);
     this.terminal.writeErrorLine(`Error: ${Logger.getErrorMessage(error)}`);
-    if (this._shouldPrintStacks && error.stack) {
+    if (this.#shouldPrintStacks && error.stack) {
       this.terminal.writeErrorLine(error.stack);
     }
   }
@@ -65,14 +65,14 @@ export class Logger implements ILogger {
    * {@inheritdoc ILogger.emitWarning}
    */
   public emitWarning(warning: Error): void {
-    this._warnings.push(warning);
+    this.#warnings.push(warning);
     this.terminal.writeWarningLine(`Warning: ${Logger.getErrorMessage(warning)}`);
-    if (this._shouldPrintStacks && warning.stack) {
+    if (this.#shouldPrintStacks && warning.stack) {
       this.terminal.writeWarningLine(warning.stack);
     }
   }
 
-  private get _shouldPrintStacks(): boolean {
-    return this._options.getShouldPrintStacks();
+  get #shouldPrintStacks(): boolean {
+    return this.#options.getShouldPrintStacks();
   }
 }
diff --git a/libraries/rush-lib/src/utilities/AsyncRecycler.ts b/libraries/rush-lib/src/utilities/AsyncRecycler.ts
index eb63ca734b1..ccf89277358 100644
--- a/libraries/rush-lib/src/utilities/AsyncRecycler.ts
+++ b/libraries/rush-lib/src/utilities/AsyncRecycler.ts
@@ -16,9 +16,9 @@ import { IS_WINDOWS } from './executionUtilities';
  * background process to recursively delete that folder.
  */
 export class AsyncRecycler {
-  private _movedFolderCount: number;
-  private _deleting: boolean;
-  private _prefix: string;
+  #movedFolderCount: number;
+  #deleting: boolean;
+  #prefix: string;
 
   /**
    * The full path of the recycler folder.
@@ -28,9 +28,9 @@ export class AsyncRecycler {
 
   public constructor(recyclerFolder: string) {
     this.recyclerFolder = path.resolve(recyclerFolder);
-    this._movedFolderCount = 0;
-    this._deleting = false;
-    this._prefix = `${Date.now()}`;
+    this.#movedFolderCount = 0;
+    this.#deleting = false;
+    this.#prefix = `${Date.now()}`;
   }
 
   /**
@@ -39,7 +39,7 @@ export class AsyncRecycler {
    * deleteAll() must be called to actually delete the contents of the recycler folder.
    */
   public moveFolder(folderPath: string): void {
-    if (this._deleting) {
+    if (this.#deleting) {
       throw new Error('AsyncRecycler.moveFolder() must not be called after deleteAll() has started');
     }
 
@@ -51,7 +51,7 @@ export class AsyncRecycler {
       return;
     }
 
-    ++this._movedFolderCount;
+    ++this.#movedFolderCount;
 
     // We need to do a simple "fs.renameSync" here, however if the folder we're trying to rename
     // has a lock, or if its destination container doesn't exist yet,
@@ -63,7 +63,7 @@ export class AsyncRecycler {
     Utilities.createFolderWithRetry(this.recyclerFolder);
 
     Utilities.retryUntilTimeout(
-      () => this._renameOrRecurseInFolder(folderPath),
+      () => this.#renameOrRecurseInFolder(folderPath),
       maxWaitTimeMs,
       (e) =>
         new Error(`Error: ${e}\nOften this is caused by a file lock from a process like the virus scanner.`),
@@ -86,7 +86,7 @@ export class AsyncRecycler {
       if (!excludeSet.has(normalizedMemberName)) {
         const absolutePath: string = path.resolve(folderPath, dirent.name);
         if (dirent.isDirectory()) {
-          this._renameOrRecurseInFolder(absolutePath);
+          this.#renameOrRecurseInFolder(absolutePath);
         } else {
           FileSystem.deleteFile(absolutePath);
         }
@@ -102,15 +102,15 @@ export class AsyncRecycler {
    * MUST NOT be called again after deleteAll() has started.
    */
   public async startDeleteAllAsync(): Promise<void> {
-    if (this._deleting) {
+    if (this.#deleting) {
       throw new Error(
         `${AsyncRecycler.name}.${this.startDeleteAllAsync.name}() must not be called more than once`
       );
     }
 
-    this._deleting = true;
+    this.#deleting = true;
 
-    if (this._movedFolderCount === 0) {
+    if (this.#movedFolderCount === 0) {
       // Nothing to do
       return;
     }
@@ -183,9 +183,9 @@ export class AsyncRecycler {
     process.unref();
   }
 
-  private _renameOrRecurseInFolder(folderPath: string): void {
-    const ordinal: number = this._movedFolderCount++;
-    const targetDir: string = `${this.recyclerFolder}/${this._prefix}_${ordinal}`;
+  #renameOrRecurseInFolder(folderPath: string): void {
+    const ordinal: number = this.#movedFolderCount++;
+    const targetDir: string = `${this.recyclerFolder}/${this.#prefix}_${ordinal}`;
     try {
       fs.renameSync(folderPath, targetDir);
       return;
@@ -203,7 +203,7 @@ export class AsyncRecycler {
     for (const child of children) {
       const absoluteChild: string = `${folderPath}/${child.name}`;
       if (child.isDirectory()) {
-        this._renameOrRecurseInFolder(absoluteChild);
+        this.#renameOrRecurseInFolder(absoluteChild);
       } else {
         FileSystem.deleteFile(absoluteChild);
       }
diff --git a/libraries/rush-lib/src/utilities/CollatedTerminalProvider.ts b/libraries/rush-lib/src/utilities/CollatedTerminalProvider.ts
index d83701011c3..b5c93d3f0ff 100644
--- a/libraries/rush-lib/src/utilities/CollatedTerminalProvider.ts
+++ b/libraries/rush-lib/src/utilities/CollatedTerminalProvider.ts
@@ -9,28 +9,28 @@ export interface ICollatedTerminalProviderOptions {
 }
 
 export class CollatedTerminalProvider implements ITerminalProvider {
-  private readonly _collatedTerminal: CollatedTerminal;
-  private _hasErrors: boolean = false;
-  private _hasWarnings: boolean = false;
-  private _debugEnabled: boolean = false;
+  readonly #collatedTerminal: CollatedTerminal;
+  #hasErrors: boolean = false;
+  #hasWarnings: boolean = false;
+  #debugEnabled: boolean = false;
 
   public readonly supportsColor: boolean = true;
   public readonly eolCharacter: string = '\n';
 
   public get hasErrors(): boolean {
-    return this._hasErrors;
+    return this.#hasErrors;
   }
 
   public get hasWarnings(): boolean {
-    return this._hasWarnings;
+    return this.#hasWarnings;
   }
 
   public constructor(
     collatedTerminal: CollatedTerminal,
     options?: Partial<ICollatedTerminalProviderOptions>
   ) {
-    this._collatedTerminal = collatedTerminal;
-    this._debugEnabled = !!options?.debugEnabled;
+    this.#collatedTerminal = collatedTerminal;
+    this.#debugEnabled = !!options?.debugEnabled;
   }
 
   public write(data: string, severity: TerminalProviderSeverity): void {
@@ -40,28 +40,28 @@ export class CollatedTerminalProvider implements ITerminalProvider {
         // Unlike the basic ConsoleTerminalProvider, verbose messages are always passed
         // to stdout -- by convention the user-controlled build script output is sent
         // to verbose, and will be routed to a variety of other providers in the ProjectBuilder.
-        this._collatedTerminal.writeChunk({ text: data, kind: TerminalChunkKind.Stdout });
+        this.#collatedTerminal.writeChunk({ text: data, kind: TerminalChunkKind.Stdout });
         break;
       }
 
       case TerminalProviderSeverity.debug: {
         // Similar to the basic ConsoleTerminalProvider, debug messages are discarded
         // unless they are explicitly enabled.
-        if (this._debugEnabled) {
-          this._collatedTerminal.writeChunk({ text: data, kind: TerminalChunkKind.Stdout });
+        if (this.#debugEnabled) {
+          this.#collatedTerminal.writeChunk({ text: data, kind: TerminalChunkKind.Stdout });
         }
         break;
       }
 
       case TerminalProviderSeverity.error: {
-        this._collatedTerminal.writeChunk({ text: data, kind: TerminalChunkKind.Stderr });
-        this._hasErrors = true;
+        this.#collatedTerminal.writeChunk({ text: data, kind: TerminalChunkKind.Stderr });
+        this.#hasErrors = true;
         break;
       }
 
       case TerminalProviderSeverity.warning: {
-        this._collatedTerminal.writeChunk({ text: data, kind: TerminalChunkKind.Stderr });
-        this._hasWarnings = true;
+        this.#collatedTerminal.writeChunk({ text: data, kind: TerminalChunkKind.Stderr });
+        this.#hasWarnings = true;
         break;
       }
 
diff --git a/libraries/rush-lib/src/utilities/HotlinkManager.ts b/libraries/rush-lib/src/utilities/HotlinkManager.ts
index 24d0ad027c6..3257255996c 100644
--- a/libraries/rush-lib/src/utilities/HotlinkManager.ts
+++ b/libraries/rush-lib/src/utilities/HotlinkManager.ts
@@ -59,20 +59,20 @@ interface IRushLinkOptions {
 const PROJECT_LINKS_STATE_JSON_SCHEMA: JsonSchema = JsonSchema.fromLoadedObject(schema);
 
 export class HotlinkManager {
-  private _linksBySubspaceName: LinksBySubspaceNameMap;
-  private readonly _rushLinkStateFilePath: string;
+  #linksBySubspaceName: LinksBySubspaceNameMap;
+  readonly #rushLinkStateFilePath: string;
 
   private constructor(options: IRushLinkOptions) {
     const { rushLinkStateFilePath, linksBySubspaceName } = options;
-    this._rushLinkStateFilePath = rushLinkStateFilePath;
-    this._linksBySubspaceName = linksBySubspaceName;
+    this.#rushLinkStateFilePath = rushLinkStateFilePath;
+    this.#linksBySubspaceName = linksBySubspaceName;
   }
 
   public hasAnyHotlinksInSubspace(subspaceName: string): boolean {
-    return !!this._linksBySubspaceName.get(subspaceName)?.length;
+    return !!this.#linksBySubspaceName.get(subspaceName)?.length;
   }
 
-  private async _hardLinkToLinkedPackageAsync(
+  async #hardLinkToLinkedPackageAsync(
     terminal: ITerminal,
     sourcePath: string,
     targetFolder: Set<string>,
@@ -98,16 +98,16 @@ export class HotlinkManager {
     });
   }
 
-  private async _modifyAndSaveLinkStateAsync(
+  async #modifyAndSaveLinkStateAsync(
     cb: (linkState: LinksBySubspaceNameMap) => Promise<LinksBySubspaceNameMap> | LinksBySubspaceNameMap
   ): Promise<void> {
-    const newLinksBySubspaceName: LinksBySubspaceNameMap = await cb(this._linksBySubspaceName);
-    this._linksBySubspaceName = newLinksBySubspaceName;
+    const newLinksBySubspaceName: LinksBySubspaceNameMap = await cb(this.#linksBySubspaceName);
+    this.#linksBySubspaceName = newLinksBySubspaceName;
     const linkStateJson: IProjectLinksStateJson = {
       fileVersion: 0,
       linksBySubspace: Object.fromEntries(newLinksBySubspaceName)
     };
-    await JsonFile.saveAsync(linkStateJson, this._rushLinkStateFilePath);
+    await JsonFile.saveAsync(linkStateJson, this.#rushLinkStateFilePath);
   }
 
   public async purgeLinksAsync(terminal: ITerminal, subspaceName: string): Promise<boolean> {
@@ -119,7 +119,7 @@ export class HotlinkManager {
       PnpmSyncUtilities.processLogMessage(logMessageOptions, terminal);
     };
 
-    await this._modifyAndSaveLinkStateAsync(async (linksBySubspaceName) => {
+    await this.#modifyAndSaveLinkStateAsync(async (linksBySubspaceName) => {
       const rushLinkFileState: IProjectLinkInSubspaceJson[] = linksBySubspaceName.get(subspaceName) ?? [];
       await Async.forEachAsync(
         rushLinkFileState,
@@ -150,7 +150,7 @@ export class HotlinkManager {
     return true;
   }
 
-  private async _getLinkedPackageInfoAsync(linkedPackagePath: string): Promise<ILinkedPackageInfo> {
+  async #getLinkedPackageInfoAsync(linkedPackagePath: string): Promise<ILinkedPackageInfo> {
     const linkedPackageJsonPath: string = `${linkedPackagePath}/${FileConstants.PackageJson}`;
 
     const linkedPackageJsonExists: boolean = await FileSystem.existsAsync(linkedPackageJsonPath);
@@ -185,7 +185,7 @@ export class HotlinkManager {
     };
   }
 
-  private async _getPackagePathsMatchingNameAndVersionAsync(
+  async #getPackagePathsMatchingNameAndVersionAsync(
     consumerPackagePnpmDependenciesFolderPath: string,
     packageName: string,
     versionRange: string
@@ -214,11 +214,11 @@ export class HotlinkManager {
   ): Promise<void> {
     const subspaceName: string = subspace.subspaceName;
     try {
-      const { packageName } = await this._getLinkedPackageInfoAsync(linkedPackagePath);
+      const { packageName } = await this.#getLinkedPackageInfoAsync(linkedPackagePath);
       const consumerPackagePnpmDependenciesFolderPath: string = `${subspace.getSubspaceTempFolderPath()}/${
         RushConstants.nodeModulesFolderName
       }/${RushConstants.pnpmVirtualStoreFolderName}`;
-      const sourcePathSet: Set<string> = await this._getPackagePathsMatchingNameAndVersionAsync(
+      const sourcePathSet: Set<string> = await this.#getPackagePathsMatchingNameAndVersionAsync(
         consumerPackagePnpmDependenciesFolderPath,
         packageName,
         version
@@ -228,8 +228,8 @@ export class HotlinkManager {
           `Cannot find package ${packageName} ${version} in ${consumerPackagePnpmDependenciesFolderPath}`
         );
       }
-      await this._hardLinkToLinkedPackageAsync(terminal, linkedPackagePath, sourcePathSet, subspaceName);
-      await this._modifyAndSaveLinkStateAsync((linksBySubspaceName) => {
+      await this.#hardLinkToLinkedPackageAsync(terminal, linkedPackagePath, sourcePathSet, subspaceName);
+      await this.#modifyAndSaveLinkStateAsync((linksBySubspaceName) => {
         const newConsumerPackageLinks: IProjectLinkInSubspaceJson[] = [
           ...(linksBySubspaceName.get(subspaceName) ?? [])
         ];
@@ -275,7 +275,7 @@ export class HotlinkManager {
   ): Promise<void> {
     const consumerPackageName: string = consumerPackage.packageName;
     try {
-      const { packageName: linkedPackageName } = await this._getLinkedPackageInfoAsync(linkedPackagePath);
+      const { packageName: linkedPackageName } = await this.#getLinkedPackageInfoAsync(linkedPackagePath);
 
       const slashIndex: number = linkedPackageName.indexOf('/');
       const [scope, packageBaseName] =
@@ -301,7 +301,7 @@ export class HotlinkManager {
       });
 
       // Record the link information between the consumer package and the linked package
-      await this._modifyAndSaveLinkStateAsync((linksBySubspaceName) => {
+      await this.#modifyAndSaveLinkStateAsync((linksBySubspaceName) => {
         const subspaceName: string = consumerPackage.subspace.subspaceName;
         const newConsumerPackageLinks: IProjectLinkInSubspaceJson[] = [
           ...(linksBySubspaceName.get(subspaceName) ?? [])
diff --git a/libraries/rush-lib/src/utilities/OverlappingPathAnalyzer.ts b/libraries/rush-lib/src/utilities/OverlappingPathAnalyzer.ts
index 826a5e7255a..084e5e33c15 100644
--- a/libraries/rush-lib/src/utilities/OverlappingPathAnalyzer.ts
+++ b/libraries/rush-lib/src/utilities/OverlappingPathAnalyzer.ts
@@ -12,14 +12,14 @@ interface IPathTreeNode<TLabel> {
  * 'lib/x' and 'lib/y' do not.
  */
 export class OverlappingPathAnalyzer<TLabel> {
-  private readonly _root: IPathTreeNode<TLabel> = {
+  readonly #root: IPathTreeNode<TLabel> = {
     encounteredLabels: new Set<TLabel>(),
     paths: {}
   };
 
   public addPathAndGetFirstEncounteredLabels(path: string, label: TLabel): TLabel[] | undefined {
     const pathParts: string[] = path.split('/');
-    let currentNode: IPathTreeNode<TLabel> = this._root;
+    let currentNode: IPathTreeNode<TLabel> = this.#root;
     let currentNodeIsNew: boolean = false;
     let labelWasAlreadyPresentInCurrentNode: boolean = false;
     for (const pathPart of pathParts) {
diff --git a/libraries/rush-lib/src/utilities/RushAlerts.ts b/libraries/rush-lib/src/utilities/RushAlerts.ts
index abca0c70577..1cbe2dd64ad 100644
--- a/libraries/rush-lib/src/utilities/RushAlerts.ts
+++ b/libraries/rush-lib/src/utilities/RushAlerts.ts
@@ -58,12 +58,12 @@ const enum AlertPriority {
 }
 
 export class RushAlerts {
-  private readonly _terminal: ITerminal;
+  readonly #terminal: ITerminal;
 
-  private readonly _rushAlertsConfig: IRushAlertsConfig | undefined;
-  private readonly _rushAlertsState: IRushAlertsState;
+  readonly #rushAlertsConfig: IRushAlertsConfig | undefined;
+  readonly #rushAlertsState: IRushAlertsState;
 
-  private readonly _rushJsonFolder: string;
+  readonly #rushJsonFolder: string;
   public readonly rushAlertsStateFilePath: string;
   public readonly rushAlertsConfigFilePath: string;
 
@@ -105,12 +105,12 @@ export class RushAlerts {
       rushAlertsConfig,
       rushAlertsState = {}
     } = options;
-    this._terminal = terminal;
-    this._rushJsonFolder = rushJsonFolder;
+    this.#terminal = terminal;
+    this.#rushJsonFolder = rushJsonFolder;
     this.rushAlertsStateFilePath = rushAlertsStateFilePath;
     this.rushAlertsConfigFilePath = rushAlertsConfigFilePath;
-    this._rushAlertsConfig = rushAlertsConfig;
-    this._rushAlertsState = rushAlertsState;
+    this.#rushAlertsConfig = rushAlertsConfig;
+    this.#rushAlertsState = rushAlertsState;
   }
 
   public static async loadFromConfigurationAsync(
@@ -148,12 +148,12 @@ export class RushAlerts {
     });
   }
 
-  private _ensureAlertStateIsUpToDate(): void {
+  #ensureAlertStateIsUpToDate(): void {
     // ensure `temp/rush-alerts.json` is up to date
-    if (this._rushAlertsConfig) {
-      for (const alert of this._rushAlertsConfig.alerts) {
-        if (!(alert.alertId in this._rushAlertsState)) {
-          this._rushAlertsState[alert.alertId] = {
+    if (this.#rushAlertsConfig) {
+      for (const alert of this.#rushAlertsConfig.alerts) {
+        if (!(alert.alertId in this.#rushAlertsState)) {
+          this.#rushAlertsState[alert.alertId] = {
             snooze: false
           };
         }
@@ -162,23 +162,23 @@ export class RushAlerts {
   }
 
   public async printAlertsAsync(): Promise<void> {
-    if (!this._rushAlertsConfig || this._rushAlertsConfig.alerts.length === 0) return;
+    if (!this.#rushAlertsConfig || this.#rushAlertsConfig.alerts.length === 0) return;
 
-    this._ensureAlertStateIsUpToDate();
+    this.#ensureAlertStateIsUpToDate();
 
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
 
-    const alert: IRushAlertsConfigEntry | undefined = await this._selectAlertByPriorityAsync();
+    const alert: IRushAlertsConfigEntry | undefined = await this.#selectAlertByPriorityAsync();
     if (alert) {
-      this._printMessageInBoxStyle(alert);
-      this._rushAlertsState[alert.alertId].lastDisplayTime = new Date().toISOString();
+      this.#printMessageInBoxStyle(alert);
+      this.#rushAlertsState[alert.alertId].lastDisplayTime = new Date().toISOString();
     }
 
-    await this._writeRushAlertStateAsync();
+    await this.#writeRushAlertStateAsync();
   }
 
   public async printAllAlertsAsync(): Promise<void> {
-    const allAlerts: IRushAlertsConfigEntry[] = this._rushAlertsConfig?.alerts ?? [];
+    const allAlerts: IRushAlertsConfigEntry[] = this.#rushAlertsConfig?.alerts ?? [];
 
     const activeAlerts: IRushAlertsConfigEntry[] = [];
     const snoozedAlerts: IRushAlertsConfigEntry[] = [];
@@ -186,15 +186,15 @@ export class RushAlerts {
 
     await Promise.all(
       allAlerts.map(async (alert) => {
-        const isAlertValid: boolean = await this._isAlertValidAsync(alert);
-        const alertState: IRushAlertStateEntry = this._rushAlertsState[alert.alertId];
+        const isAlertValid: boolean = await this.#isAlertValidAsync(alert);
+        const alertState: IRushAlertStateEntry = this.#rushAlertsState[alert.alertId];
 
         if (!isAlertValid) {
           inactiveAlerts.push(alert);
           return;
         }
 
-        if (this._isSnoozing(alertState)) {
+        if (this.#isSnoozing(alertState)) {
           snoozedAlerts.push(alert);
           return;
         }
@@ -203,53 +203,53 @@ export class RushAlerts {
       })
     );
 
-    this._printAlerts(activeAlerts, 'active');
-    this._printAlerts(snoozedAlerts, 'snoozed');
-    this._printAlerts(inactiveAlerts, 'inactive');
+    this.#printAlerts(activeAlerts, 'active');
+    this.#printAlerts(snoozedAlerts, 'snoozed');
+    this.#printAlerts(inactiveAlerts, 'inactive');
   }
 
-  private _printAlerts(alerts: IRushAlertsConfigEntry[], status: AlertStatus): void {
+  #printAlerts(alerts: IRushAlertsConfigEntry[], status: AlertStatus): void {
     if (alerts.length === 0) return;
     switch (status) {
       case 'active':
       case 'inactive':
-        this._terminal.writeLine(Colorize.yellow(`The following alerts are currently ${status}:`));
+        this.#terminal.writeLine(Colorize.yellow(`The following alerts are currently ${status}:`));
         break;
       case 'snoozed':
-        this._terminal.writeLine(Colorize.yellow('The following alerts are currently active but snoozed:'));
+        this.#terminal.writeLine(Colorize.yellow('The following alerts are currently active but snoozed:'));
         break;
     }
     alerts.forEach(({ title }) => {
-      this._terminal.writeLine(Colorize.green(`"${title}"`));
+      this.#terminal.writeLine(Colorize.green(`"${title}"`));
     });
-    this._terminal.writeLine();
+    this.#terminal.writeLine();
   }
 
   public async snoozeAlertsByAlertIdAsync(alertId: string, forever: boolean = false): Promise<void> {
-    this._ensureAlertStateIsUpToDate();
+    this.#ensureAlertStateIsUpToDate();
     if (forever) {
-      this._rushAlertsState[alertId].snooze = true;
+      this.#rushAlertsState[alertId].snooze = true;
     } else {
-      this._rushAlertsState[alertId].snooze = true;
+      this.#rushAlertsState[alertId].snooze = true;
       const snoozeEndTime: Date = new Date();
       snoozeEndTime.setDate(snoozeEndTime.getDate() + 7);
-      this._rushAlertsState[alertId].snoozeEndTime = snoozeEndTime.toISOString();
+      this.#rushAlertsState[alertId].snoozeEndTime = snoozeEndTime.toISOString();
     }
-    await this._writeRushAlertStateAsync();
+    await this.#writeRushAlertStateAsync();
   }
 
-  private async _selectAlertByPriorityAsync(): Promise<IRushAlertsConfigEntry | undefined> {
-    const alerts: Array<IRushAlertsConfigEntry> = this._rushAlertsConfig!.alerts;
-    const alertsState: IRushAlertsState = this._rushAlertsState;
+  async #selectAlertByPriorityAsync(): Promise<IRushAlertsConfigEntry | undefined> {
+    const alerts: Array<IRushAlertsConfigEntry> = this.#rushAlertsConfig!.alerts;
+    const alertsState: IRushAlertsState = this.#rushAlertsState;
 
     const needDisplayAlerts: Array<IRushAlertsConfigEntry> = (
       await Promise.all(
         alerts.map(async (alert) => {
-          const isAlertValid: boolean = await this._isAlertValidAsync(alert);
+          const isAlertValid: boolean = await this.#isAlertValidAsync(alert);
           const alertState: IRushAlertStateEntry = alertsState[alert.alertId];
           if (
             isAlertValid &&
-            !this._isSnoozing(alertState) &&
+            !this.#isSnoozing(alertState) &&
             (!alertState.lastDisplayTime ||
               Number(new Date()) - Number(new Date(alertState.lastDisplayTime)) >
                 RushAlerts.alertDisplayIntervalDurations.get(
@@ -271,14 +271,14 @@ export class RushAlerts {
     return alertsSortedByPriority[0];
   }
 
-  private _isSnoozing(alertState: IRushAlertStateEntry): boolean {
+  #isSnoozing(alertState: IRushAlertStateEntry): boolean {
     return (
       Boolean(alertState.snooze) &&
       (!alertState.snoozeEndTime || Number(new Date()) < Number(new Date(alertState.snoozeEndTime)))
     );
   }
 
-  private async _isAlertValidAsync(alert: IRushAlertsConfigEntry): Promise<boolean> {
+  async #isAlertValidAsync(alert: IRushAlertsConfigEntry): Promise<boolean> {
     const timeNow: Date = new Date();
 
     if (alert.startTime) {
@@ -308,7 +308,7 @@ export class RushAlerts {
             JSON.stringify(conditionScript)
         );
       }
-      const conditionScriptPath: string = `${this._rushJsonFolder}/common/config/rush/alert-scripts/${conditionScript}`;
+      const conditionScriptPath: string = `${this.#rushJsonFolder}/common/config/rush/alert-scripts/${conditionScript}`;
       if (!(await FileSystem.existsAsync(conditionScriptPath))) {
         throw new Error(
           'The "conditionScript" field in rush-alerts.json refers to a nonexistent file:\n' +
@@ -316,7 +316,7 @@ export class RushAlerts {
         );
       }
 
-      this._terminal.writeDebugLine(`Invoking condition script "${conditionScript}" from rush-alerts.json`);
+      this.#terminal.writeDebugLine(`Invoking condition script "${conditionScript}" from rush-alerts.json`);
       const startTimemark: number = performance.now();
 
       interface IAlertsConditionScriptModule {
@@ -342,7 +342,7 @@ export class RushAlerts {
       try {
         // "Rush will invoke this script with the working directory set to the monorepo root folder,
         // with no guarantee that `rush install` has been run."
-        process.chdir(this._rushJsonFolder);
+        process.chdir(this.#rushJsonFolder);
         conditionResult = conditionScriptModule.canShowAlert();
 
         if (typeof conditionResult !== 'boolean') {
@@ -357,7 +357,7 @@ export class RushAlerts {
       }
 
       const totalMs: number = performance.now() - startTimemark;
-      this._terminal.writeDebugLine(
+      this.#terminal.writeDebugLine(
         `Invoked conditionScript "${conditionScript}"` +
           ` in ${Math.round(totalMs)} ms with result "${conditionResult}"`
       );
@@ -369,7 +369,7 @@ export class RushAlerts {
     return true;
   }
 
-  private _printMessageInBoxStyle(alert: IRushAlertsConfigEntry): void {
+  #printMessageInBoxStyle(alert: IRushAlertsConfigEntry): void {
     const boxTitle: string = alert.title.toUpperCase();
 
     const boxMessage: string = typeof alert.message === 'string' ? alert.message : alert.message.join('');
@@ -405,16 +405,16 @@ export class RushAlerts {
     }
 
     // Print the box
-    this._terminal.writeLine('╔═' + '═'.repeat(lineLength) + '═╗');
+    this.#terminal.writeLine('╔═' + '═'.repeat(lineLength) + '═╗');
     for (const line of lines) {
-      this._terminal.writeLine(`║ ${line.padEnd(lineLength)} ║`);
+      this.#terminal.writeLine(`║ ${line.padEnd(lineLength)} ║`);
     }
-    this._terminal.writeLine('╚═' + '═'.repeat(lineLength) + '═╝');
-    this._terminal.writeLine(`To stop seeing this alert, run "rush alert --snooze ${alert.alertId}"`);
+    this.#terminal.writeLine('╚═' + '═'.repeat(lineLength) + '═╝');
+    this.#terminal.writeLine(`To stop seeing this alert, run "rush alert --snooze ${alert.alertId}"`);
   }
 
-  private async _writeRushAlertStateAsync(): Promise<void> {
-    await JsonFile.saveAsync(this._rushAlertsState, this.rushAlertsStateFilePath, {
+  async #writeRushAlertStateAsync(): Promise<void> {
+    await JsonFile.saveAsync(this.#rushAlertsState, this.rushAlertsStateFilePath, {
       ignoreUndefinedValues: true,
       headerComment: '// THIS FILE IS MACHINE-GENERATED -- DO NOT MODIFY',
       jsonSyntax: JsonSyntax.JsonWithComments
diff --git a/libraries/rush-lib/src/utilities/Stopwatch.ts b/libraries/rush-lib/src/utilities/Stopwatch.ts
index e137f27e140..d4eac852ad0 100644
--- a/libraries/rush-lib/src/utilities/Stopwatch.ts
+++ b/libraries/rush-lib/src/utilities/Stopwatch.ts
@@ -39,24 +39,24 @@ export interface IStopwatchResult {
  * of elapsed time in between two events.
  */
 export class Stopwatch implements IStopwatchResult {
-  private _startTime: number | undefined;
-  private _endTime: number | undefined;
-  private _state: StopwatchState;
+  #startTime: number | undefined;
+  #endTime: number | undefined;
+  #state: StopwatchState;
 
-  private _getTime: () => number;
+  #getTime: () => number;
 
   public constructor(getTime: () => number = Utilities.getTimeInMs) {
-    this._startTime = undefined;
-    this._endTime = undefined;
-    this._getTime = getTime;
-    this._state = StopwatchState.Stopped;
+    this.#startTime = undefined;
+    this.#endTime = undefined;
+    this.#getTime = getTime;
+    this.#state = StopwatchState.Stopped;
   }
 
   public static fromState({ startTime, endTime }: { startTime: number; endTime: number }): Stopwatch {
     const stopwatch: Stopwatch = new Stopwatch();
-    stopwatch._startTime = startTime;
-    stopwatch._endTime = endTime;
-    stopwatch._state = StopwatchState.Stopped;
+    stopwatch.#startTime = startTime;
+    stopwatch.#endTime = endTime;
+    stopwatch.#state = StopwatchState.Stopped;
     return stopwatch;
   }
 
@@ -68,7 +68,7 @@ export class Stopwatch implements IStopwatchResult {
   }
 
   public get state(): StopwatchState {
-    return this._state;
+    return this.#state;
   }
 
   /**
@@ -76,12 +76,12 @@ export class Stopwatch implements IStopwatchResult {
    * reset() should be called before calling start() again.
    */
   public start(startTimeOverride?: number): Stopwatch {
-    if (this._startTime !== undefined) {
+    if (this.#startTime !== undefined) {
       throw new Error('Call reset() before starting the Stopwatch');
     }
-    this._startTime = startTimeOverride ?? this._getTime();
-    this._endTime = undefined;
-    this._state = StopwatchState.Started;
+    this.#startTime = startTimeOverride ?? this.#getTime();
+    this.#endTime = undefined;
+    this.#state = StopwatchState.Started;
     return this;
   }
 
@@ -89,8 +89,8 @@ export class Stopwatch implements IStopwatchResult {
    * Stops executing the stopwatch and saves the current timestamp
    */
   public stop(): Stopwatch {
-    this._endTime = this._startTime !== undefined ? this._getTime() : undefined;
-    this._state = StopwatchState.Stopped;
+    this.#endTime = this.#startTime !== undefined ? this.#getTime() : undefined;
+    this.#state = StopwatchState.Stopped;
     return this;
   }
 
@@ -98,8 +98,8 @@ export class Stopwatch implements IStopwatchResult {
    * Resets all values of the stopwatch back to the original
    */
   public reset(): Stopwatch {
-    this._endTime = this._startTime = undefined;
-    this._state = StopwatchState.Stopped;
+    this.#endTime = this.#startTime = undefined;
+    this.#state = StopwatchState.Stopped;
     return this;
   }
 
@@ -107,7 +107,7 @@ export class Stopwatch implements IStopwatchResult {
    * Displays how long the stopwatch has been executing in a human readable format.
    */
   public toString(): string {
-    if (this._state === StopwatchState.Stopped && this._startTime === undefined) {
+    if (this.#state === StopwatchState.Stopped && this.#startTime === undefined) {
       return '0.00 seconds (stopped)';
     }
     const totalSeconds: number = this.duration;
@@ -126,25 +126,25 @@ export class Stopwatch implements IStopwatchResult {
    * Get the duration in seconds.
    */
   public get duration(): number {
-    if (this._startTime === undefined) {
+    if (this.#startTime === undefined) {
       return 0;
     }
-    const curTime: number = this._endTime !== undefined ? this._endTime : this._getTime();
+    const curTime: number = this.#endTime !== undefined ? this.#endTime : this.#getTime();
 
-    return (curTime - this._startTime) / 1000.0;
+    return (curTime - this.#startTime) / 1000.0;
   }
 
   /**
    * Return the start time of the most recent stopwatch run.
    */
   public get startTime(): number | undefined {
-    return this._startTime;
+    return this.#startTime;
   }
 
   /**
    * Return the end time of the most recent stopwatch run.
    */
   public get endTime(): number | undefined {
-    return this._endTime;
+    return this.#endTime;
   }
 }
diff --git a/libraries/rush-lib/src/utilities/TarExecutable.ts b/libraries/rush-lib/src/utilities/TarExecutable.ts
index 6ea2e0f4d61..db58cc902de 100644
--- a/libraries/rush-lib/src/utilities/TarExecutable.ts
+++ b/libraries/rush-lib/src/utilities/TarExecutable.ts
@@ -28,10 +28,10 @@ export interface ICreateArchiveOptions extends ITarOptionsBase {
 }
 
 export class TarExecutable {
-  private _tarExecutablePath: string;
+  #tarExecutablePath: string;
 
   private constructor(tarExecutablePath: string) {
-    this._tarExecutablePath = tarExecutablePath;
+    this.#tarExecutablePath = tarExecutablePath;
   }
 
   public static async tryInitializeAsync(terminal: ITerminal): Promise<TarExecutable | undefined> {
@@ -52,7 +52,7 @@ export class TarExecutable {
    * The "tar" exit code
    */
   public async tryUntarAsync(options: IUntarOptions): Promise<number> {
-    return await this._spawnTarWithLoggingAsync(
+    return await this.#spawnTarWithLoggingAsync(
       // These parameters are chosen for compatibility with the very primitive bsdtar 3.3.2 shipped with Windows 10.
       [
         // [Windows bsdtar 3.3.2] Extract: tar -x [options] [<patterns>]
@@ -82,7 +82,7 @@ export class TarExecutable {
     await FileSystem.ensureFolderAsync(path.dirname(archivePath));
 
     const projectFolderPath: string = project.projectFolder;
-    const tarExitCode: number = await this._spawnTarWithLoggingAsync(
+    const tarExitCode: number = await this.#spawnTarWithLoggingAsync(
       // These parameters are chosen for compatibility with the very primitive bsdtar 3.3.2 shipped with Windows 10.
       [
         // [Windows bsdtar 3.3.2] -c Create
@@ -105,7 +105,7 @@ export class TarExecutable {
     return tarExitCode;
   }
 
-  private async _spawnTarWithLoggingAsync(
+  async #spawnTarWithLoggingAsync(
     args: string[],
     currentWorkingDirectory: string,
     logFilePath: string,
@@ -141,7 +141,7 @@ export class TarExecutable {
     fileWriter.write(
       [
         `Start time: ${new Date().toString()}`,
-        `Invoking "${this._tarExecutablePath} ${args.join(' ')}"`,
+        `Invoking "${this.#tarExecutablePath} ${args.join(' ')}"`,
         '',
         `======= BEGIN PROCESS INPUT ======`,
         input || '',
@@ -151,7 +151,7 @@ export class TarExecutable {
       ].join('\n')
     );
 
-    const childProcess: ChildProcess = Executable.spawn(this._tarExecutablePath, args, {
+    const childProcess: ChildProcess = Executable.spawn(this.#tarExecutablePath, args, {
       currentWorkingDirectory: currentWorkingDirectory
     });