Microsoft

Microsoft Teams , a workplace collaboration app designed to rival Slack, suffered an outage Monday after Microsoft failed to renew its authentication certificate. The tool was down for about three hours while Microsoft investigated and updated the certificate, according to the company's Twitter account. By around 9 a.m. PT Monday, the service was back up for most users though the issue wasn't fully resolved until later in the day.

"We've addressed an access issue that some customers may have experienced, and service is fully restored," a Microsoft spokesperson told CNET in an email Monday.

Microsoft acknowledged the problem in a tweet at 6:19 a.m. PT.

We're investigating an issue where users may be unable to access Microsoft Teams. We're reviewing systems data to determine the cause of the issue. More information can be found in the Admin center under TM202916 — Microsoft 365 Status (@MSFT365Status) February 3, 2020

The company announced the full fix in a tweet at 1:27 p.m. PT.

We successfully deployed the fix to the affected infrastructure and conducted additional remediation actions to resolve the issue. More information can be found under TM202916. — Microsoft 365 Status (@MSFT365Status) February 3, 2020

Microsoft Teams is a communication platform for businesses that includes chat, video meetings and file storage.

Originally published Feb. 3.

Update, Feb. 4: Adds comment from Microsoft.