Microsoft Teams has been down for a number of users, primarily in Europe, for several hours this morning, March 16. Microsoft officials posted that they'd mitigated the issue, only to re-open it again after continued user reports of problems.
Around 4:50 a.m. ET, the Microsoft 365 Status account on Twitter posted that Microsoft was "investigating messaging-related functionality problems within Microsoft Teams." On Twitter, users were reporting not just messaging issues, but also problems adding guests to Teams and issues switching tenants.
Around 7 a.m. ET, the Microsoft 365 Status account posted that the chat issues in Teams had been mitigated. However, some users were still reporting outages. At 10:30 a.m. ET, the account noted that Microsoft was receiving reports that Teams communications issues had resumed. Microsoft is re-investigating the issue and advising administrators that they will get updates on the situation under TM206556 in their admin centers.
There's no time that's good for a Teams outage. And with many assigned to work remotely due to the COVID-19 coronavirus, plus numerous industry events being moved to virtual, it's an especially tough time for Teams to be down.
Update (2:45 p.m. ET): The Microsoft 365 Status account just posted this update, saying they believe the issue has now been mitigated (hopefully for the last time today).
"We've rerouted user connections to alternate systems and our monitoring indicates that impact is mitigated. We've confirmed that the impact associated with TM206559 is related to TM206556 and will continue to update TM206556 with the latest status as we monitor service health."