Millions of Microsoft 365 users around the world were unable to open their email, join meetings or reach their files on Thursday, after a major outage struck Outlook, Teams and other Microsoft services. Reports of problems began in the afternoon in the United States and rose sharply through the evening, with outage tracker Downdetector recording more than 130,000 reports about Outlook in the US alone at the peak. Microsoft said a large number of its servers had unexpectedly become unavailable, leaving the systems still running overloaded. The company said it was working to bring servers back into service, but by Friday morning many people were still facing disruption.
FAKTA
- What happened: A worldwide Microsoft 365 outage disrupted Outlook, Teams and other services from Thursday afternoon.
- Scale: More than 130,000 Outlook problem reports at the peak in the United States, according to Downdetector.
- Cause, as Microsoft described it: Servers unexpectedly became unavailable, overloading the systems still running. Not a surge in user traffic, and not a cyberattack.
- Recovery: Microsoft is restarting servers and moving traffic elsewhere; partial recovery was reported, but full restoration had not been confirmed.
- Also affected: OpenAI and Anthropic reported problems with their Microsoft connectors; Australia's spy agency and federal police were also hit.
What went wrong
Microsoft first said it was investigating reports of users unable to reach Exchange Online mailboxes, the system behind Outlook email. It later confirmed the problem could affect Microsoft 365 connectivity in every region. In updates posted on its Microsoft 365 Status account, the company said part of its infrastructure was under unusual strain. It later said a core process on the affected servers was becoming overwhelmed, causing them to stop responding. Microsoft ruled out a sudden rise in traffic. It said it had paused new deployments, was moving traffic away from the affected infrastructure and was restarting servers to return them to service.
A long day for users and businesses
The disruption reached far beyond email. Microsoft said users could be unable to connect to Exchange Online, Teams, SharePoint Online, Copilot, Defender, Planner, To Do, Intune, Purview and Power BI. The effects spread to other companies too. OpenAI said it was investigating a fault with its Microsoft connectors, and Anthropic reported an issue with an upstream supplier affecting its own Microsoft 365 connector. In Australia, the spy agency and the federal police confirmed they were affected. Electric truck maker Workhorse Group postponed its quarterly results announcement, blaming the outage.
Recovery under way, but no root cause yet
By Thursday evening in the United States, Microsoft said it had observed limited recovery as users gradually reconnected, and Downdetector reports had fallen sharply from the peak. The company’s service health page still listed the outage as service degradation early on Friday. Microsoft has not published a root cause, saying only that servers became unavailable during automated health checks. The incident is tracked as EX1550543 in the Microsoft 365 admin centre. More technology coverage is available on Watan News.
