Overview
- A fast-moving outage began on Thursday, Nov. 12, and quickly spread to about 74 countries, with outage tracker Downdetector recording roughly 130,000–140,000 reports for Outlook at the peak.
- Microsoft says the problem was not a traffic surge but a number of servers failing health checks, which overloaded the remaining infrastructure and disrupted Exchange Online, Outlook, Teams and Copilot.
- Engineers paused deployments, restarted and rebuilt affected servers, redistributed traffic and tested configuration changes but reported that some fixes 'did not take as expected' and restored servers could become unresponsive again.
- The disruption has cascaded to third-party integrations and customers, with OpenAI and Anthropic reporting connector failures and governments and businesses reporting email and productivity impacts.
- Microsoft reports no indication of malicious activity, continues to issue service‑health updates under incident EX1550543, and says it will provide a full root‑cause report once services are fully recovered.