Reports of Microsoft 365 trouble began arriving around midday Thursday, with Outlook users unable to reach their inboxes on the web or through apps. Outage reports surged just before 1 p.m. ET and remained elevated, even as Microsoft’s own status pages were difficult to load.¹

The disruption quickly proved broader than email. Users reported problems with Teams, while Microsoft said the outage was affecting services including SharePoint, Copilot, Defender XDR, OneDrive and Office for the web. The company initially pointed to “elevated load” across infrastructure in multiple regions and said it was redistributing connection traffic worldwide.²

By the afternoon, Microsoft said it had not identified a recent change that matched the start of the incident. Its investigation instead focused on failed health checks and a server component that might be causing them. The company began testing a change to bypass that component on some servers, while also investigating unusually high processor use and trying to return unavailable servers to service.¹

The outage continued for hours, with reports spanning Asia and the United States and affecting companies as well as some government operations.³ Microsoft later attributed the incident to “a large number of servers being unexpectedly unavailable,” without explaining why they had failed.²

There was no clear restoration timetable in the reports, and the full extent of the disruption remained uncertain. The episode also revived memories of a major Microsoft 365 outage in September, which the company blamed on a core authentication configuration problem.²