Outlook won’t open on Windows 11? Microsoft 365 outage could be the reason

• Microsoft confirmed connectivity problems affecting Exchange Online and other Microsoft 365 services on November 12, 2026.
• Downdetector recorded nearly 130,000 reports of Outlook problems shortly after 1 p.m. ET.
• Microsoft traced the infrastructure problems to servers unexpectedly becoming unavailable after failing automated health checks.
• Windows 11 users should check Microsoft’s service status before repairing or reinstalling Outlook.

If Microsoft Outlook won’t open, connect, or load email on Windows 11, the problem may not be your computer. Microsoft is experiencing a widespread outage affecting Exchange Online and several Microsoft 365 services on November 12, 2026.

The disruption is preventing some users from accessing their mailboxes, sending or receiving emails, and connecting to Microsoft’s services. The problems affect multiple connection methods, including Outlook desktop and Outlook on the web.

According to the Associated Press, more than 120,000 users reported problems accessing Outlook on Downdetector around 1:30PM ET. Users also reported problems with Microsoft Teams, Copilot, and other Microsoft 365 services.

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Microsoft acknowledged the Exchange Online problems through its Microsoft 365 Status account on X, initially reporting connectivity issues in the Americas. The company later warned that the disruption could affect users in other regions.

The company initially attributed the connectivity errors to elevated loads across multiple regions. However, Microsoft later clarified that the problem wasn’t caused by increased traffic but by several servers becoming unexpectedly unavailable.

Microsoft identified a possible problem with a component responsible for processing server health checks. The company said it was testing a configuration change, restarting affected servers, and redirecting traffic to other infrastructure to restore service.

As of the latest service health update on November 12, the software giant still lists a service degradation affecting Microsoft 365 business and enterprise customers. The company says users may be unable to connect to multiple services, including Exchange Online.

If Outlook won’t open or connect on Windows 11, check the Microsoft 365 service status before repairing or reinstalling the application.

If the problem is caused by the ongoing outage, resetting Outlook, creating a new profile, or reinstalling the application won’t fix the underlying issue.

Wait for Microsoft to restore the affected services before attempting additional troubleshooting. If Outlook continues to experience problems after the outage is resolved, you can investigate local application issues, check your internet connection, or repair your Outlook installation.