diff --git a/src/vs/vscode.proposed.d.ts b/src/vs/vscode.proposed.d.ts
index 083c74124bd..706ebf4325d 100644
--- a/src/vs/vscode.proposed.d.ts
+++ b/src/vs/vscode.proposed.d.ts
@@ -1745,4 +1745,18 @@ declare module 'vscode' {
 	}
 
 	//#endregion
+
+	//#region https://github.com/microsoft/vscode/issues/90517
+
+	export interface FileSystemError {
+		/**
+		 * A code that identifies this error.
+		 *
+		 * Possible values are names of errors, like [`FileNotFound`](#FileSystemError.FileNotFound),
+		 * or `undefined` for an unspecified error.
+		 */
+		readonly code?: string;
+	}
+
+	////#endregion
 }
diff --git a/src/vs/workbench/api/common/extHostFileSystem.ts b/src/vs/workbench/api/common/extHostFileSystem.ts
index a721785d28c..ca30ef0d660 100644
--- a/src/vs/workbench/api/common/extHostFileSystem.ts
+++ b/src/vs/workbench/api/common/extHostFileSystem.ts
@@ -148,7 +148,16 @@ class ConsumerFileSystem implements vscode.FileSystem {
 		}
 
 		// file system error
-		throw new FileSystemError(err.message, err.name as files.FileSystemProviderErrorCode);
+		switch (err.name) {
+			case files.FileSystemProviderErrorCode.FileExists: throw FileSystemError.FileExists(err.message);
+			case files.FileSystemProviderErrorCode.FileNotFound: throw FileSystemError.FileNotFound(err.message);
+			case files.FileSystemProviderErrorCode.FileNotADirectory: throw FileSystemError.FileNotADirectory(err.message);
+			case files.FileSystemProviderErrorCode.FileIsADirectory: throw FileSystemError.FileIsADirectory(err.message);
+			case files.FileSystemProviderErrorCode.NoPermissions: throw FileSystemError.NoPermissions(err.message);
+			case files.FileSystemProviderErrorCode.Unavailable: throw FileSystemError.Unavailable(err.message);
+
+			default: throw new FileSystemError(err.message, err.name as files.FileSystemProviderErrorCode);
+		}
 	}
 }
 
diff --git a/src/vs/workbench/api/common/extHostTypes.ts b/src/vs/workbench/api/common/extHostTypes.ts
index e7810d7b6a3..0c62c89ad01 100644
--- a/src/vs/workbench/api/common/extHostTypes.ts
+++ b/src/vs/workbench/api/common/extHostTypes.ts
@@ -2333,9 +2333,13 @@ export class FileSystemError extends Error {
 		return new FileSystemError(messageOrUri, FileSystemProviderErrorCode.Unavailable, FileSystemError.Unavailable);
 	}
 
+	readonly code?: string;
+
 	constructor(uriOrMessage?: string | URI, code: FileSystemProviderErrorCode = FileSystemProviderErrorCode.Unknown, terminator?: Function) {
 		super(URI.isUri(uriOrMessage) ? uriOrMessage.toString(true) : uriOrMessage);
 
+		this.code = terminator?.name;
+
 		// mark the error as file system provider error so that
 		// we can extract the error code on the receiving side
 		markAsFileSystemProviderError(this, code);
diff --git a/src/vs/workbench/services/log/common/keyValueLogProvider.ts b/src/vs/workbench/services/log/common/keyValueLogProvider.ts
index 0db6b00da32..9180d49303e 100644
--- a/src/vs/workbench/services/log/common/keyValueLogProvider.ts
+++ b/src/vs/workbench/services/log/common/keyValueLogProvider.ts
@@ -4,7 +4,7 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { URI } from 'vs/base/common/uri';
-import { IFileSystemProviderWithFileReadWriteCapability, FileSystemProviderCapabilities, IFileChange, IWatchOptions, IStat, FileOverwriteOptions, FileType, FileDeleteOptions, FileWriteOptions, FileChangeType, FileSystemProviderErrorCode } from 'vs/platform/files/common/files';
+import { IFileSystemProviderWithFileReadWriteCapability, FileSystemProviderCapabilities, IFileChange, IWatchOptions, IStat, FileOverwriteOptions, FileType, FileDeleteOptions, FileWriteOptions, FileChangeType } from 'vs/platform/files/common/files';
 import { Disposable, IDisposable } from 'vs/base/common/lifecycle';
 import { Event, Emitter } from 'vs/base/common/event';
 import { VSBuffer } from 'vs/base/common/buffer';
@@ -53,13 +53,13 @@ export abstract class KeyValueLogProvider extends Disposable implements IFileSys
 				size: 0
 			};
 		}
-		return Promise.reject(new FileSystemError(resource, FileSystemProviderErrorCode.FileNotFound));
+		return Promise.reject(FileSystemError.FileNotFound(resource));
 	}
 
 	async readdir(resource: URI): Promise<[string, FileType][]> {
 		const hasKey = await this.hasKey(resource.path);
 		if (hasKey) {
-			return Promise.reject(new FileSystemError(resource, FileSystemProviderErrorCode.FileNotADirectory));
+			return Promise.reject(FileSystemError.FileNotADirectory(resource));
 		}
 		const keys = await this.getAllKeys();
 		const files: Map<string, [string, FileType]> = new Map<string, [string, FileType]>();
@@ -79,7 +79,7 @@ export abstract class KeyValueLogProvider extends Disposable implements IFileSys
 	async readFile(resource: URI): Promise<Uint8Array> {
 		const hasKey = await this.hasKey(resource.path);
 		if (!hasKey) {
-			return Promise.reject(new FileSystemError(resource, FileSystemProviderErrorCode.FileNotFound));
+			return Promise.reject(FileSystemError.FileNotFound(resource));
 		}
 		const value = await this.getValue(resource.path);
 		return VSBuffer.fromString(value).buffer;
@@ -90,7 +90,7 @@ export abstract class KeyValueLogProvider extends Disposable implements IFileSys
 		if (!hasKey) {
 			const files = await this.readdir(resource);
 			if (files.length) {
-				return Promise.reject(new FileSystemError(resource, FileSystemProviderErrorCode.FileIsADirectory));
+				return Promise.reject(FileSystemError.FileIsADirectory(resource));
 			}
 		}
 		await this.setValue(resource.path, VSBuffer.wrap(content).toString());