Microsoft Says Microsoft 365 Is Fully Restored After Global Outage

Thursday's workday in the Americas ran into a familiar wall: Outlook wouldn't load, Teams faltered, and the reports piled up faster than Microsoft could answer them. Microsoft 365, the subscription suite that carries email and meetings for a large share of offices, went down for thousands of users, according to outage tracker Downdetector.

Reports began building just after noon Eastern, and Microsoft's status account acknowledged the problem at 12:54 p.m., saying it was investigating reports of users unable to access Exchange Online mailboxes through multiple connection methods in the Americas. Newsrooms were among the offices affected; at least one television station told viewers on air that its own Outlook was down while it reported the story.

The peak came early in the afternoon. Downdetector recorded more than 130,000 reports of problems with Outlook at about 1:27 p.m. Eastern, more than 46,000 reports for Microsoft 365 itself, and roughly 3,000 for Teams. The affected services, per Microsoft's own incident updates, included Exchange Online, Teams, SharePoint Online, Microsoft 365 Copilot and Defender XDR, tracked under incidents EX1550543 and MO1550821.

Microsoft's explanation, as the afternoon went on, was specific about what it wasn't. A large number of the company's own servers became unexpectedly unavailable, the company said, and the failed health checks that followed were traced to a specific health-processing component. There had been no correlated change to the system, and Microsoft said nothing points to a cyberattack.

The response was the standard playbook executed at scale. Microsoft paused all deployments, moved traffic away from the affected infrastructure, and restarted servers. By about 4 p.m., the company said it had validated an alternative health-check method that was bringing some servers back. Downdetector's curve bent the right way: by early evening, Outlook reports had fallen to roughly 33,000 and Microsoft 365 reports to about 11,000.

It was the second disruption of the day. Microsoft said earlier on Thursday that it had fixed a separate Teams problem affecting users in North America and that the impact had been fully resolved, before the larger failure built.

As of Thursday evening the company hadn't declared the incident over, and the reports, while falling, hadn't reached zero. For the offices that route their entire day through one suite, the outage was a working demonstration of the trade: everything in one place is convenient right up until the one place has an afternoon like this. Microsoft also cautioned, as the incident developed, that the issue could affect Microsoft 365 service connectivity for users in other regions beyond the Americas.

Update, Saturday: Microsoft said Saturday that Microsoft 365 service is fully restored, closing the outage tracked as incident MO1550821 — the disruption that took down Outlook, Teams and Copilot across more than 70 countries for over a day, hitting governments, businesses and hospitals that run on the suite. The company announced the restoration on its official channels; the cause remains the one it gave Thursday, its own servers becoming unexpectedly unavailable, with nothing pointing to a cyberattack.