Overview
- A large-scale outage on Thursday, Nov. 12 knocked users offline from Exchange Online/Outlook and other Microsoft 365 apps as error reports on Downdetector spiked into the hundreds of thousands.
- Microsoft says the problem began when a number of servers failed health checks and became unavailable, which shifted load onto remaining systems and reduced capacity.
- Engineers have paused deployments, redistributed connection traffic, tested configuration reversions, and restarted affected servers while monitoring telemetry for gradual recovery.
- The disruption touched multiple services including Teams, Copilot, SharePoint Online and Defender XDR, forced some government and university offices to use contingencies, and left administrators directed to incident EX1550543 in the Microsoft 365 admin center for updates.
- The outage follows earlier Microsoft incidents this year and has drawn scrutiny from national cyber authorities and customers because it highlights how centralizing email and collaboration on a few cloud providers increases systemic risk.