A global Microsoft outage disrupted Outlook, Teams and the wider Microsoft 365 suite for more than five hours on Thursday, November 12, leaving thousands of users unable to open mailboxes, send email or join meetings, Reuters reported. Microsoft was still working to return affected servers to service on Thursday evening Eastern Time and said it had observed limited recovery as users gradually reconnected.
Source: Reuters via SecurityAffairs, Nov 12, 2026
Outage tracker Downdetector logged a peak of 138,058 reports of Outlook problems at around 1 p.m. ET, according to reports citing the tracker. By Thursday evening the Outlook figure had fallen to about 34,490, and reports of wider Microsoft 365 problems had dropped to nearly 13,000 by 5:47 p.m. ET.
Source: ANI, Nov 13, 2026
Microsoft said the main disruption, tracked as incident MO1550821, began at 1:26 p.m. ET and could affect users in any region. Services named in its notices included Exchange Online, Outlook, Microsoft Teams, SharePoint Online, OneDrive, Word, Excel, PowerPoint, Microsoft 365 Copilot and Microsoft Defender XDR. A separate Teams incident, TM1550488, had affected users in North and South America from 9:45 to 10:53 a.m. ET earlier in the day.
Source: Microsoft 365 service health via Modern Scot, Nov 12, 2026
On cause, Microsoft said the elevated load was not driven by an increase in traffic: a number of servers had become unexpectedly unavailable, straining the infrastructure that remained. Its updates said servers had failed automated health checks, pushing extra load onto machines still running, and that it had paused deployments, moved traffic off the affected infrastructure and begun restarting servers and returning some of them to service.
Source: Reuters via SecurityAffairs, Nov 12, 2026
A Microsoft spokesperson said the company had no indication of a cyber attack, according to The Guardian's report of the outage. No final root cause had been confirmed in the reports reviewed, and Microsoft said recovery would be gradual as capacity returned and clients reconnected.
Source: The Guardian via Stocks99, Nov 13, 2026
The failure reached beyond Microsoft's own products. OpenAI said it was investigating an issue with its Microsoft connectors, warning that new connections might be broken and tools might not work as expected. Anthropic said an issue with an upstream provider was affecting its Microsoft 365 connector.
Source: Reuters via SecurityAffairs, Nov 12, 2026
By early Friday morning in Asia the disruption was still being felt further east: Downdetector figures reported from Singapore rose through the morning as businesses there opened, even as counts in the United States continued to fall from the peak.
Source: Tech360TV, Nov 13, 2026
What happens next: Microsoft had not declared the incident fully resolved in its late-Thursday updates. Users and businesses that depend on Outlook email and Teams meetings should expect gradual restoration rather than an instant return, and further company updates on the cause once its checks on a possible recent change are complete.