A global outage of Microsoft 365 services locked millions of users, businesses, and government agencies across multiple continents out of their accounts. The disruption began around 18:00 GMT on Thursday, November 12, and lasted for nearly 16 hours, affecting core tools including Outlook, Exchange Online, Teams, Word, Excel, and PowerPoint.
According to Downdetector logs, the incident initially generated roughly 130,000 outage reports worldwide. In the United States alone, reports topped 97,000 for Outlook, 38,000 for Microsoft 365, and 4,500 for Teams, underscoring the scale of the disruption.
On Friday, November 13, Microsoft reported gradual recovery progress, noting service improvements in Europe and North America alongside relative stability in Japan. However, the company acknowledged that intermittent issues persisted and extended its retry window to 48 hours to protect delayed messages while engineers worked to clear email backlogs.
According to technical updates posted on its service health portal, the outage stemmed from a configuration update that caused a cluster of servers to overload and unexpectedly disconnect. That disruption automatically rerouted traffic to the remaining servers, which quickly became overwhelmed and triggered a cascading failure across Exchange Online.
Recovery efforts took longer because the affected servers repeatedly stopped responding when engineers applied patches, restarted them and restored traffic. To contain the problem, the company selectively restricted access in certain locations, optimized traffic flows and rolled back some servers to an earlier software configuration.
Amid speculation about possible cyberattacks, Microsoft said it had found no evidence of malicious activity related to the incident. The company stated that mitigation and stabilization efforts would continue until the affected platforms returned to normal operation.
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Finally, the technology giant announced that it would publish a comprehensive post-incident report once recovery operations were complete, providing details about the causes of the outage and the measures taken to prevent a similar failure from disrupting its services worldwide again.
