Many users of Microsoft Teams were unable to connect to the platform's web or desktop apps for several hours on Monday, a day when more employees than usual were working from home because of the Presidents Day holiday.
Reports of connectivity issues began shortly after 8 a.m. EST and peaked between 9 a.m. and 10 a.m. EST, according to the tracking site downdetector.com, which is owned by internet metrics firm Ookla. The problem impacted users of the Microsoft Teams app globally.
Microsoft said on Twitter that connectivity issues related to the Microsoft Teams app were resolved by around 2 p.m. EST. It was not immediately clear what caused the problem.
"We've implemented a configuration change to Teams authentication infrastructure which resolved Teams connectivity issues," Microsoft tweeted.
Justin Young, IT operations manager at Oetiker Inc., a midsize global manufacturing firm, said his users were able to access the mobile app and make phone calls all day. The issue for his company was limited to the desktop and web apps.
Incidents like this demonstrate why IT professionals have to set reasonable expectations when adopting cloud services. Young's firm is in the process of a company-wide rollout of the Microsoft Teams app.
"Whenever there is a hiccup in the middle of [a rollout], then you're going to have management kind of look at you sideways and wonder, is this the right choice?" Young said. "You really are at the mercy of the provider."
In this case, Young said Microsoft was able to restore service quickly enough to avoid violating its service-level agreement. Microsoft has reported quarterly uptimes between 99.97% and 99.99% in each quarter over the past two years.
Monday's multi-hour outage makes it difficult for Microsoft to argue Teams is more reliable than competing apps like Slack and Cisco Webex Teams, said Irwin Lazar, analyst at Nemertes Research.
"For buyers, it means further caution and a need for due diligence when evaluating cloud providers," Lazar said. "It also means that as customers integrate business processes into their team apps, they need to ensure they have contingency plans when there is an outage."
Microsoft has labeled Teams as its fastest-growing app in history. In September, the company said more than 329,000 organizations were using the collaboration service, although it did not say how many users were regularly active on the platform.
Slack has also dealt with connectivity issues as it has grown rapidly. A string of outages between mid-2017 and mid-2018 led some analysts to question whether Slack was developing a reputation for unreliability.
Slack has not reported a connectivity issue since October.