Microsoft 365 outage: Service to Teams, Outlook restored to many users, company says

Microsoft 365 services, including the communication platforms Microsoft Teams and Outlook, had been disrupted across North America, the software company said, but by Thursday night, the number of outages had gone down considerably.

Some users had encountered “degraded service functionality,” while others may be entirely unable to access the services, the company said on its service health status webpage. The company blamed it on an issue related to "load balancing," meaning the way traffic is distributed over multiple servers to prevent overloading.

"We’re seeing continued improvements in service availability and functionality as a result of our load-balancing efforts," the company said in a post on X Thursday night. "We’re actively monitoring performance and making targeted adjustments to further improve stability and availability, while continuing recovery actions to ensure a reliable service experience.

By 9:47 p.m., less than 700 Microsoft 365 service outages were reported, according to Down Detector, a website that tracks disruptions to various cellphone, internet and other services. That was down from a high of almost 16,000 reported outages around 3 p.m.

In an early evening update, the company said that during its "efforts to rebalance traffic across the region, we introduced a targeted load balancing configuration change intended to expedite the recovery process, which incidentally introduced additional traffic imbalances associated with persistent impact for a portion of the affected infrastructure.

"We're remedying our load balancing configurations while, in parallel, reviewing the viability of expediting our ongoing incremental rebalancing and recovery efforts," Microsoft said.

The root cause of the disruption has been traced to “a portion of dependent service infrastructure in the North America region,” which has not been “processing traffic as expected,” the company said.

Error messages were appearing as users attempted to send and receive emails via Outlook. Other hampered services include the cloud-based email and calendar Exchange Online and cloud services Microsoft OneDrive and SharePoint Online.

Newsday's Robert Brodsky contributed to this story.