United StatesDowndetector logged 130,000 Outlook outage reports at the peak.
Outlook, Teams and Copilot failed in 74 countries within an hour, Downdetector data show.
Servers failing automated health checks went offline, and Microsoft says the strain on the rest, not extra traffic, caused the overload.
Microsoft has not found a recent change that coincided with the start of the outage.
Microsoft is bypassing the failing health-check component and has not said when service fully returns.
How each outlet framed it
drawn from 600+ reports worldwide
- The New York Times
- BBC
- relays Microsoft's update that it is testing a configuration change after servers failed automated health checks, with all affected servers restarted
- Hindustan Times
- quotes Microsoft's Exchange Online ticket reference EX1550543 and its statement that the issue can affect users in any region
- Al Jazeera Online
- Mashable SEA
- reports Microsoft's theory that a health-check component on affected servers may be behind the failures, and its targeted bypass of that component
Sources: The New York Times, BBC, Hindustan Times, Al Jazeera Online, Mashable SEA