Microsoft 365 Outage Takes Down Outlook, Teams, and Copilot Worldwide

Microsoft confirmed a major Microsoft 365 outage on November 12, with its own service health advisory (MO1550821) reporting the incident began at 1:26 PM ET. The disruption hit Exchange Online, Microsoft Teams, SharePoint Online, Microsoft 365 Copilot, and Microsoft Defender XDR, according to Microsoft's advisory, while user reports on Downdetector also named Outlook, Azure, OneDrive, and the Microsoft Store among the affected services. Microsoft initially described the problem as limited to the Americas before confirming that users in any region could be affected.

Microsoft said it had been investigating Exchange Online mailbox connectivity issues in the Americas earlier the same day, and that a number of servers became unexpectedly unavailable, placing extra strain on the remaining infrastructure. In a statement posted to X, the company said the added load was not the result of higher-than-normal traffic. Its mitigation steps have included pausing all deployments, redistributing connection traffic away from the affected systems, and restarting the servers involved. A separate, shorter Teams incident (TM1550488) that ran from 9:45 to 10:53 AM ET in North and South America was resolved earlier in the day; Microsoft has not said whether the two incidents are related.

Outages at this scale are costly less because of the outage itself than because of how deeply Microsoft 365 sits underneath everyday business operations — email, meetings, document collaboration, and increasingly, Copilot-assisted work, all routing through the same set of cloud services. A multi-hour disruption to Exchange Online and Teams simultaneously means missed meetings, stalled approvals, and support queues piling up at exactly the volume a company's own IT and communications channels, which often also run on Microsoft 365, are least equipped to handle. Security teams face a secondary complication: with Microsoft Defender XDR also listed among the affected services, organizations lose visibility into some threat detection during the same window.

As of Microsoft's most recent update, the main Microsoft 365 incident had not been resolved, though the company said it was working to safely return affected servers to service. Microsoft has not given a timeline for full restoration or detailed what caused servers to become unavailable in the first place.