Microsoft's global cloud outage disrupts email, Teams, and AI tools for 18 hours

Microsoft is gradually restoring services after a day-long global outage that began with Outlook and Teams and expanded to much of its cloud, affecting email, files, and AI tools. The company reports no evidence of malicious activity. The cascading software issue started Thursday in the U.S. and spread worldwide, knocking out consumer and business email, Copilot AI, Defender security software, and admin dashboards. Engineers struggled to recover downed servers, with traffic returning after about 18 hours, according to Kentik. Microsoft has not identified the root cause, citing “a large number of servers being unexpectedly unavailable.” The incident follows a September outage blamed on an authentication configuration issue, and the company faces questions about its recovery speed.