Microsoft Teams desktop app hangs on Windows as Mac users lose call access

Key points

• Microsoft confirmed a Teams desktop launch problem on Windows at 16:45 EDT Thursday, tracked internally as TM1466820, with load delays of up to two minutes.
• A separate issue, tracked as TM1466659, is stopping some Mac users from joining Teams calls and meetings, confirmed at 10:57 EDT the same day.
• Microsoft first blamed a code change for the Mac call failures but is now reassessing after further review.
• The company is telling affected Windows users to work around the launch issue by using Teams on the web or the mobile app.
• Both incidents are still open, with engineers pulling service logs and telemetry to find the cause.

Microsoft Teams, the chat and video calling app used by millions of office workers, is having a rough Thursday. Two separate problems are stopping people getting into the service properly, one on Windows and one on Mac.

The first issue hits the Teams desktop app on Windows computers. When users try to open it, the app either refuses to load or takes up to two minutes to start. Microsoft acknowledged the problem, which it tracks internally as TM1466820, at 16:45 Eastern time on Thursday.

"Specifically, when first opening Microsoft Teams on Windows devices, some users may be initially unable to load the client or may encounter loading delays of up to two minutes," Microsoft said in an incident report first reported by BleepingComputer.

The suggested workaround is simple: open Teams in a web browser, or use the phone app.

What is going wrong for Mac users?

Mac users are hitting a different wall. Some cannot join calls or meetings at all. Microsoft confirmed this second issue, tracked as TM1466659, at 10:57 EDT on Thursday.

Engineers first pointed the finger at a recent code change that they thought was causing Teams' call and meeting infrastructure to drop some requests. That theory did not hold up.

"We're reassessing our root cause understanding and reviewing service logs to isolate the source of impact, so that we can determine our next steps regarding impact remediation," the company said.

In plain terms: they thought they knew what broke it, a closer look said maybe not, and now they are digging through the records again.

Should users be worried about their data?

No. These are availability problems, meaning the service is slow or unreachable, not a security breach. Nothing in Microsoft's incident notes suggests attacker involvement or exposed data. It is a bad afternoon for productivity, not a bad afternoon for your files.

That matters because Teams outages get a lot of attention, and it is easy to assume the worst. Capability and intent are different things. Right now the capability that is missing is Microsoft's own, to keep its service running smoothly.

The two open incidents at a glance

A rough month for Microsoft's collaboration stack

This is not the first wobble. In April, Microsoft fixed a bug that blocked some Teams Free users from chatting and calling. On Tuesday this week, it confirmed another bug that was crashing Teams and the new Outlook after users installed Windows security updates from the August 2026 Patch Tuesday cycle.

And earlier today the company told customers that an ongoing Exchange Online problem is delaying email between internal and external addresses, with users seeing "Server busy" errors.

For now, if Teams will not open on your work laptop, try the browser version at teams.microsoft.com or your phone. If you are on a Mac and cannot join a meeting, dial in by phone if the invite offers a number. Microsoft has not given a fix time for either issue.

This is a developing story.