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Why is New Outlook not opening on Windows 11 after the December 2025 update?
Windows 11 users are experiencing a widespread service interruption following the “New Outlook” application update released on December 5, 2025. Reports from Reddit, Microsoft Q&A, and technical forums confirm that the application fails to launch entirely.
Symptoms and Scope
The failure presents as a “silent crash.” When a user attempts to open the application, no interface loads, and the system displays no error codes or diagnostic messages. Standard troubleshooting methods—including system restarts, application reinstallation via the Microsoft Store, and execution of the olk.exe -recovery command—have proven ineffective.
It is important to note that this issue is isolated to the “New Outlook” Windows client. The classic Outlook desktop application, the outlook.com web interface, and mobile applications on iOS/Android remain fully functional.
Technical Workaround: Clearing the Cache
The current consensus for resolving this issue involves manually clearing the local application data. This forces the application to rebuild its configuration files upon the next launch.
Step-by-Step Recovery Procedure:
- Close all Office applications to ensure no files are locked.
- Open File Explorer on your Windows device.
- Paste the following path into the address bar and press Enter:
%localappdata%\Microsoft - Locate the folder named Olk. This folder contains the cached data for the New Outlook app.
- Delete the Olk folder.
Note: You may also see a folder named OneAuth. If the issue persists after deleting Olk, deleting OneAuth is a secondary troubleshooting step, though primarily related to authentication tokens. - Attempt to restart the New Outlook application.
Critical Advisory and Risks
Before proceeding with the deletion of the Olk folder, you must understand the potential side effects. Technical analyst Martin Geuß (Dr. Windows) notes that while this method restores application functionality, it resets local configurations.
If your primary Microsoft account is your default profile, the transition is usually smooth. However, secondary email accounts added to the client may be removed during this process. You should be prepared to re-authenticate and re-add any non-primary email accounts (such as Gmail, Yahoo, or secondary business accounts) after the reset.
Strategic Recommendation
If immediate access is critical and you lack the time to reconfigure accounts, we advise temporarily reverting to Outlook Classic or utilizing the Outlook Web App (OWA). These platforms are unaffected by the December 5th update bug. Alternatively, switching to a robust third-party client like Mozilla Thunderbird ensures email continuity while Microsoft engineers finalize an official patch.