Microsoft’s Outlook, Teams, and other 365 services suffered a widespread outage that stretched from Thursday into Friday, disrupting access to email, collaboration tools, and cloud-based applications across several regions.
The disruption began shortly before 1 p.m. Eastern Time on Thursday, November 12. Downdetector recorded nearly 138,000 reports of Outlook problems at the peak, although the figure represents user reports, not a confirmed count of affected customers.
Microsoft said some servers had unexpectedly become unavailable, shifting workloads to remaining systems and creating elevated demand. The company said the problem was not caused by an increase in user traffic.
To restore services, Microsoft restarted affected servers, rerouted traffic, and imposed limits to ease pressure on its systems. It also began rebuilding some servers using a previous configuration and paused deployments while troubleshooting continued.
The outage centered on Exchange Online, the service underpinning Outlook and several Microsoft 365 functions. Teams users also encountered problems, particularly with features that rely on Exchange Online, including calendar access and meeting scheduling.
Other affected services included Copilot, SharePoint, Microsoft Graph, and parts of the Microsoft 365 admin center. The disruption underscored how a problem in one core cloud service can spill over into applications used for everyday business operations.
Microsoft had not announced a definitive root cause or a timeline for full restoration in its latest updates. Its response remained focused on stabilizing affected servers, managing traffic, and validating the changes being deployed.
The incident also highlighted the dependence of businesses and organizations on Microsoft’s cloud-based productivity tools, where an interruption to a central service can disrupt several workplace applications at once.
