Workers took to social media to share that they were unable to conduct meetings while Microsoft Teams is out of action.
Those affected are unable to connect via the Windows desktop application, smartphone app or the web.
The official Microsoft 365 support Twitter page said the cause of the outage was an expired authentication certificate.
“We’re developing a fix to apply a new certificate to the service which will remediate impact. Further updates can be found under TM202916 in the admin center,” the support page said.
We've determined that an authentication certificate has expired causing, users to have issues using the service. We're developing a fix to apply a new certificate to the service which will remediate impact. Further updates can be found under TM202916 in the admin center.
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— Microsoft 365 Status (@MSFT365Status) February 3, 2020
Reports of Microsoft Teams being down started around 1:40pm GMT. The website DownDetector, which monitors site outages, showed that more than 3,000 people had reported the issue at 2:27PM.
“Certificates can take weeks to renew and mistakes are often made,” said Kevin Bocek, VP security strategy and threat intelligence at Venafi. “These mistakes can cause a service or application to go down for hours, days, and, in some cases, even longer.
“This is not a unique occurrence, and unfortunately Microsoft Azure and LinkedIn have experienced outages due to expired certificates in the past. The main issue is that certificates act as authenticators for machines, they authorise machine-to-machine connections and communications.
“Keys and certificates serve as machine identities and they are critical to making today’s global economy work. When they expire, business stops.”
The problem appears to be global. Microsoft has not said when users can expect Teams to be working again, but in its latest post said:
“We’ve initiated the deployment of the updated certificate and are monitoring service health as the fix progresses. Additional information can be found under TM202916 in the admin center.”
@MicrosoftTeams is down so I’m dialing into meetings on a regular phone like a savage.
— ☞ Scott Hoag (@ciphertxt) February 3, 2020
The service, which combines messaging, video meetings and file storage, launched in 2017 and is seen as a competitor to Slack.
Verdict has contacted Microsoft and will update this page when there is any news.
Update 09:36 AM 04/02/2020: A Microsoft spokesperson said: “We’ve addressed an access issue that some customers may have experienced, and service is fully restored.”