Microsoft services disrupted for over five hours, affecting businesses and AI services

On November 12, several Microsoft online services were disrupted for more than five hours. Microsoft 365, Outlook and Teams were affected, impacting thousands of users. Microsoft service connections used by OpenAI and Anthropic were also affected.

A Microsoft sign in New York, United States.（VietVance）

Microsoft said some servers had unexpectedly shut down, leaving its systems unable to handle the increased workload. The outage was not caused by a sudden surge in traffic. As of 6 p.m. Eastern Time on November 12, Microsoft was still restoring the affected servers, and some users had begun reconnecting. The company was rerouting traffic through alternative connections and said users might regain access gradually as applications reconnected.

Data from outage tracking site Downdetector showed that reports of Outlook problems peaked at about 138,058 around 1 p.m. on November 12, before falling to about 34,490 that evening. By 5:47 p.m., reports of Microsoft 365 problems had fallen to nearly 13,000, while 763 reports of difficulty accessing Teams remained.

OpenAI said it was investigating problems with Microsoft service connections; new connections could be disrupted, and some tools might not work as expected. Anthropic said an outage at an upstream service provider had affected its Microsoft 365 connection. Electric truck maker Workhorse Group postponed the release of its third-quarter 2026 results from November 12 to November 16, citing business disruption caused by the worldwide Microsoft outage. Microsoft’s Azure cloud platform had also experienced a service disruption the previous October.

Source: VietVance