Fix 'Cannot start Microsoft Outlook. Cannot open the Outlook window.'

Updated: 11/29/2025

You double-click Outlook to start your workday, but it refuses to open. An error pops up: 'Cannot start Microsoft Outlook. Cannot open the Outlook window. The set of folders cannot be opened.'. This usually happens because the Navigation Pane settings file (which remembers your folder layout) has become corrupted (XML error).

Method 1: Reset the Navigation Pane (The 10-Second Fix)

This command wipes the corrupted layout file and regenerates a default one. It fixes the issue 95% of the time.

Step 1: Open Run

Press Win + R on your keyboard.

Step 2: Enter Command

Type this exactly and hit Enter:

Outlook should open immediately. You might have to rearrange your folders, but the app works.

Method 2: Repair Office (Quick Repair)

If the reset didn't work, the Outlook core files might be damaged.

• Go to Control Panel > Programs and Features.
• Find Microsoft 365 (or Office 2019/2021).
• Right-click and select Change.
• Select 'Quick Repair'. This takes about 5 minutes and fixes missing registry keys.

Method 3: Create a New Outlook Profile

Your user profile might be corrupted beyond repair.

Go to Control Panel > Mail > Show Profiles. Click Add to create a new profile name (e.g., 'Work2'). Set it as the default. When you open Outlook, you will need to enter your email and password again to re-sync your mailbox.