Microsoft is recovering from a global outage that began on Thursday, November 12, and left its email, meeting and cloud services unreliable for about a day.
The company has not said what caused the failure. It described the problem as "a large number of servers being unexpectedly unavailable" and said it was still investigating.
The disruption was first reported in the United States and the Americas. It then spread around the world while engineers struggled to bring the affected servers back online.
The trouble began with Outlook email and Teams video calls. It grew to affect consumer and business email, as well as files and documents stored in the cloud.
Microsoft's Copilot AI tools, Defender security screening and Intune administration dashboards were also hit. Some users had trouble reaching cloud-based Windows computers.
The outage affected many industries. Engineers had initially been unable to find the cause.
By Friday morning on the U.S. East Coast, Outlook had begun to recover and some emails were arriving. Doug Madory, director of internet analysis at Kentik, said traffic to Microsoft's services was returning after about 18 hours of downtime.
In its Friday status update, Microsoft said there was "no evidence of malicious activity associated with this incident." A Microsoft spokesperson did not respond to questions about whether the company can detect malicious activity or check what happened.
The previous major Microsoft outage came in September. It lasted several days, and the company blamed it on a "core authentication configuration" issue.
