Earlier today, Microsoft Teams users were unable to access the workplace chat and collaboration platform. Microsoft confirmed the service was down and it remained so for around three hours. In an embarrassing situation for Microsoft, the reason for the crash was because the company forgot to renew a security license.

Users of Microsoft Teams found error messages when they tried to sing in. According to that message, the app was not establishing an HTTPS connection with Microsoft servers.

Microsoft released a post just after 9AM ET on Monday to confirm the issue. The company then returned with the following information:

“We’ve determined that an authentication certificate has expired causing users to have issues using the service,” explains Microsoft’s outage notification.

Later, Microsoft started rolling the fix out at 11:20AM ET, and less than an hour later Microsoft Teams was completely restored.

Teams Growth

Microsoft could have done without this error as the timing was terrible. The company has been talking up the abilities of Teams compared to rival Slack. In fact, the company is currently running ads to advertise the platform.

Microsoft has been celebrating the success of Teams. The company confirmed the platform has over 20 million Daily Active Users (DAUs). This number is significantly higher than Slack’s 12 million. However, Slack quickly refuted Microsoft’s numbers as not as impressive as they seem. Later, a CNBC survey has found Microsoft Teams is used twice as much as Slack.

Microsoft says Teams had 220 million filed edited, stored, or opened on its platform last month. As Slack points out, this would only mean 11 monthly actions related to files per active daily users.