A major Microsoft 365 outage knocked out Outlook, parts of Teams, and Copilot for users around the world on Thursday, November 12. Microsoft 365 is the company's cloud subscription service that includes Outlook and Teams.
Problems began shortly before 1 p.m. ET and stretched into Friday morning in parts of Asia. Downdetector received outage reports from 74 countries and territories within about an hour.
Microsoft said several servers became unexpectedly unavailable, placing additional strain on the remaining systems. By Thursday night, the outage had run for more than 12 hours. Businesses, government offices, and traders all felt the impact.
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In the US, about 130,000 users reported Outlook problems soon after 1 p.m. ET, according to Downdetector. About 37,000 still reported issues by 6 p.m. ET. People struggled to open mailboxes, and emails arrived late.
Teams calendar and meeting-scheduling features failed, although core chat and meeting functions mostly continued to work. Copilot could not reach emails, calendars, and files. Microsoft said it was 'not aware of any malicious activity' behind the problem. The company also admitted that its first fixes did not work as expected.
Engineers later applied a patch to part of the infrastructure. A configuration fix for authentication and routing followed, and Microsoft added server capacity. Tools from OpenAI and Anthropic that link to Microsoft services were also hit.
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Bloomberg called it one of Microsoft's longest outages, noting that earlier disruptions rarely lasted more than several hours. At least one company postponed a quarterly earnings call, CNN reported.
Microsoft had not confirmed full recovery when the latest reports came out, and it gave no firm timeline. Admins can follow updates in the Microsoft 365 admin center under incident MO1550821. The outage highlights the importance of backup communication channels for companies that rely on a single provider.