The online suite of Microsoft 365 services, including the messaging and conferencing app Teams, was affected for several hours on Monday evening thanks to an issue caused by “a recent change to an authentication system”, according to the technology giant.
A status update from Microsoft said: “Any service that leverages Azure Active Directory (AAD) may be affected.
“This includes but is not limited to Microsoft Teams, Forms, Exchange Online, Intune and Yammer.”
While not all users were affected, the issue appeared to be causing problems worldwide and Microsoft said it “could affect any user”.
The Seattle-based company attempted to roll back the update that caused the problem, but the fix took “longer than expected” and was not complete until nearly 10pm UK time – more than two hours after it started to look into the issue.
A tweet from the Microsoft 365 Status read: “The update has finished deployment to all impacted regions.
“Microsoft 365 services are showing decreasing error rates in telemetry.
“We’ll continue to monitor service health status.”
Some gamers were unable to access their Xbox Live accounts, while the online premiere of Zack Snyder’s Justice League had to be delayed because of the issue.
In America, some schools that were using Teams for remote learning were also affected.
Microsoft said last October that Microsoft Teams had 115 million active users per day.