diff --git a/packages/core/src/browser/window/window-service.ts b/packages/core/src/browser/window/window-service.ts
index e06d903e7c67a..7286a8e8a7116 100644
--- a/packages/core/src/browser/window/window-service.ts
+++ b/packages/core/src/browser/window/window-service.ts
@@ -26,9 +26,9 @@ export interface NewWindowOptions {
 export const WindowService = Symbol('WindowService');
 
 /**
- *  The window hash value that is used to spawn a new default window.
+ * The window hash value that is used to spawn a new default window.
  */
-export const DEFAULT_WINDOW_HASH: string = '#!empty';
+export const DEFAULT_WINDOW_HASH: string = '!empty';
 
 export interface WindowService {
 
diff --git a/packages/core/src/electron-main/electron-main-application.ts b/packages/core/src/electron-main/electron-main-application.ts
index a2050bd5cf9a9..67ddc09dbb1f2 100644
--- a/packages/core/src/electron-main/electron-main-application.ts
+++ b/packages/core/src/electron-main/electron-main-application.ts
@@ -290,7 +290,9 @@ export class ElectronMainApplication {
     }
 
     protected async handleMainCommand(params: ElectronMainExecutionParams, options: ElectronMainCommandOptions): Promise<void> {
-        if (options.file === undefined) {
+        if (params.secondInstance === false) {
+            await this.openWindowWithWorkspace(''); // restore previous workspace.
+        } else if (options.file === undefined) {
             await this.openDefaultWindow();
         } else {
             let workspacePath: string | undefined;
diff --git a/packages/workspace/src/browser/workspace-service.ts b/packages/workspace/src/browser/workspace-service.ts
index 159f26f285cc6..3050f168343b8 100644
--- a/packages/workspace/src/browser/workspace-service.ts
+++ b/packages/workspace/src/browser/workspace-service.ts
@@ -130,7 +130,7 @@ export class WorkspaceService implements FrontendApplicationContribution {
     protected async doGetDefaultWorkspaceUri(): Promise<string | undefined> {
 
         // If an empty window is explicitly requested do not restore a previous workspace.
-        if (window.location.hash === DEFAULT_WINDOW_HASH) {
+        if (window.location.hash === `#${DEFAULT_WINDOW_HASH}`) {
             window.location.hash = '';
             return undefined;
         }
@@ -213,6 +213,7 @@ export class WorkspaceService implements FrontendApplicationContribution {
             this.setURLFragment('');
         }
         this.updateTitle();
+        await this.server.setMostRecentlyUsedWorkspace(this._workspace?.resource.toString() || '');
         await this.updateWorkspace();
     }
 
diff --git a/packages/workspace/src/node/default-workspace-server.ts b/packages/workspace/src/node/default-workspace-server.ts
index 409c8bce601fd..075ad3b8e4eb6 100644
--- a/packages/workspace/src/node/default-workspace-server.ts
+++ b/packages/workspace/src/node/default-workspace-server.ts
@@ -92,19 +92,10 @@ export class DefaultWorkspaceServer implements WorkspaceServer {
 
     async setMostRecentlyUsedWorkspace(uri: string): Promise<void> {
         this.root = new Deferred();
-        const listUri: string[] = [];
-        const oldListUri = await this.getRecentWorkspaces();
-        listUri.push(uri);
-        if (oldListUri) {
-            oldListUri.forEach(element => {
-                if (element !== uri && element.length > 0) {
-                    listUri.push(element);
-                }
-            });
-        }
         this.root.resolve(uri);
+        const recentRoots = Array.from(new Set([uri, ...await this.getRecentWorkspaces()]));
         this.writeToUserHome({
-            recentRoots: listUri
+            recentRoots
         });
     }