Microsoft is still working to fix a Microsoft 365 outage that has left some users unable to connect to services including Exchange Online and Microsoft Teams. In an update posted at 22:11 UTC on November 12, its service health page listed the problem as a service degradation and said users "may be unable to connect to multiple Microsoft 365 services."
The company is tracking the incident under EX1550543 and MO1550821 in the Microsoft 365 admin center. It said its next update would come by 23:30 UTC.
Services Microsoft Lists as Affected
Microsoft's service health page names these services as potentially impacted:
- Exchange Online
- Microsoft Teams
- SharePoint Online
- Microsoft 365 Copilot
- Microsoft Defender XDR
- Microsoft Planner
- Microsoft To Do
- Microsoft Intune
- Microsoft Defender for Office 365
- Microsoft Purview, including Authorization, Auto Labelling, Data Loss Prevention, Communication Compliance and Data Classification
- Power BI, where users may intermittently be unable to export reports with MIP sensitivity labels to PDF
- Microsoft 365 Apps Admin Center, including Cloud Update, Cloud Policy and Inventory
Exchange Online hosts Outlook mailboxes for work and school accounts. Microsoft's list does not name Outlook.com, its consumer email service.
How the Outage Developed
At 17:54 UTC, Microsoft's Microsoft 365 Status account said the company was investigating reports of users having trouble reaching Exchange Online mailboxes "through multiple connection methods in the Americas." At 18:07 UTC it said the issue "may affect Microsoft 365 service connectivity for users in any region."
At 18:35 UTC, Microsoft said a portion of its infrastructure was "experiencing elevated load across multiple regions, which is likely contributing to the connectivity errors." At 19:31 UTC it said the load "isn't driven by an increase in traffic, but by a number of servers being unexpectedly unavailable," which was straining the remaining infrastructure, and that it was working to return those servers to service.
In an earlier status page update, Microsoft said an alternative health check method had let a subset of the affected servers return to service and that it was applying the change more broadly. It also said it was preparing an automated process to detect and restart unresponsive servers, and that a review of recent changes had found "a small number of configuration updates" it is investigating as potential contributors.
At 21:41 UTC, Microsoft said it was restarting and validating the affected servers to return them to service and was looking for ways to speed that up. It said it was also assessing whether reverting those recent configuration updates could help recovery.
At 22:11 UTC, Microsoft said its actions so far "have not provided the anticipated relief." It said a core process on the affected servers is becoming overwhelmed, which causes the servers to stop responding and contributes to the capacity loss. To test a possible recovery approach, Microsoft said it is fully isolating a portion of its service infrastructure, restarting the affected components and gradually reintroducing traffic before applying the approach more broadly. It is also evaluating whether isolating traffic within each region could let affected regions recover independently.
Earlier Teams Incident
Earlier on November 12, Microsoft tracked a Teams problem under a different incident ID. At 15:40 UTC it said it was investigating reports of users having issues accessing or using Teams in North America, tracked as TM1550488. At 17:09 UTC it said its mitigation had restored service and that customer impact was "now fully resolved."
Where to Follow Updates
Admins can follow EX1550543 and MO1550821 under Service health in the Microsoft 365 admin center. Microsoft also posts updates on its public service health page, and Technobezz tracks the service on its Microsoft 365 status page.
If Outlook still won't connect after Microsoft says service is restored, our guides cover checking and fixing Outlook email problems, Outlook stuck on Loading Profile, Outlook stuck in Working Offline mode and Hotmail not working.
