Microsoft 365 outage disrupts Outlook, Teams and Copilot

A Microsoft 365 outage disrupted access to Outlook, Teams and Copilot on November 12 after several servers unexpectedly went offline. Microsoft said users in any region could experience connection problems and reported only limited recovery by 6:57 p.m. ET that evening.

Microsoft traced the start of the wider outage to 1:26 p.m. ET on Thursday. Earlier in the day, it had begun investigating reports from users in the Americas who could not connect to their Exchange Online mailboxes. Its subsequent advisory, which administrators could track under MO1550821, also listed SharePoint Online and Microsoft Defender XDR among the affected services.

Server failures leave less capacity for connections

Microsoft initially saw unusually high load across several regions. As engineers investigated, they found that incoming traffic had not increased. Instead, several servers had dropped out of service, leaving fewer machines to handle the usual volume of connections. Microsoft later identified a core process that was struggling to keep up on affected servers, further reducing capacity.

To ease the pressure, Microsoft paused all deployments and redirected connections across its global infrastructure. Engineers also began restarting affected servers. When those steps brought less relief than expected, the team examined whether reversing a small number of recent configuration changes could speed up recovery. Microsoft did not identify those changes as the cause of the outage.

Microsoft reports limited recovery by Thursday evening

By 6:57 p.m. ET, engineers had brought some servers back online. Those machines remained stable, and Microsoft continued to move traffic onto alternative routes. The company also shortened the process for bringing the remaining servers back into service.

For users, recovery depended in part on when their applications reconnected. Microsoft therefore expected access to return gradually. Its Thursday evening update gave no estimate for when all services would return to normal.

Earlier Teams incident delayed messages in the Americas

Hours before the wider Microsoft 365 outage, a separate Teams incident disrupted messaging in North and South America. Between 9:45 a.m. and 10:53 a.m. ET, users encountered delays or failures when sending messages. Some also had trouble retrieving chats or creating and updating conversations.

Microsoft attributed that interruption to systems competing for resources and confirmed that messaging had recovered. It tracked the incident under TM1550488 and did not say whether it shared a cause with the afternoon outage.