Microsoft has brought some unresponsive servers back online after a Microsoft 365 outage disrupted access to Outlook and Teams. The company reported improvements in some regions at 00:06 Polish time on Friday, 13 November, but users could still face difficulties accessing work email and messaging.
By Adam Ujazdowski. Polish original published on 12 November 2026 at 23:20 UTC.
The disruption began on Thursday, 12 November. Microsoft initially reported problems accessing Exchange Online mailboxes across the Americas. It later said connection errors could also affect other regions, with Teams, SharePoint Online and Microsoft 365 Copilot among the services covered by its warning.
More than 97,000 Outlook reports
Downdetector data cited by Reuters showed more than 97,000 reports concerning Outlook, over 38,000 for Microsoft 365 and about 4,500 for Teams at 14:07 US Eastern time, or 20:07 in Poland.
Users reported difficulties opening mailboxes and sending and receiving messages. Microsoft confirmed that errors affected several ways of connecting to Exchange Online, including Outlook on the web.
Earlier that day, Microsoft had resolved a separate Teams outage in North America, tracked as TM1550488. It described the subsequent disruption in notices EX1550543 and MO1550821.
Unresponsive servers put pressure on the remaining infrastructure
Microsoft found that an overloaded core process was causing some servers to stop responding, leaving the remaining machines to take over their workload. The company halted deployments, redirected traffic and began restarting servers. It was also investigating whether recent configuration changes had contributed to the outage.
At 23:11 Polish time on Thursday, Microsoft said its initial measures had not delivered the expected improvement. It began testing another approach: isolating part of the infrastructure, restarting its components and gradually restoring connections. In a subsequent update, it said the restored servers were operating stably and promised its next update by 01:30 Polish time on Friday.
AI integrations lose access to email and calendars
OpenAI said ChatGPT could encounter errors when connecting to Microsoft services and using features available through those connections. Anthropic reported problems with Claude’s Microsoft 365 integration.
At 22:18 Polish time on Thursday, Anthropic said most email and calendar queries, as well as search requests, were still failing. The disruption also affected the Claude add-in for Outlook: some users had trouble opening it and accessing email and calendars through it.
