Microsoft Outlook outage cause traced to failed server checks

Microsoft is investigating failed server health checks as a possible cause of the Nov. 12 Outlook outage and is testing a fix on affected servers, according to an X post. The company said a specific component running automated checks may have caused some servers to go offline, with heavier-than-usual load across multiple regions contributing to connection problems. Microsoft is deploying a targeted change to bypass this component on a subset of servers and has taken steps to prevent further outages. The outage initially affected Exchange Online mailboxes in the Americas, later expanding to Microsoft 365 services globally. Nearly 130,000 problem reports appeared on Downdetector by 1 p.m. ET, with Copilot and Teams users also impacted. Microsoft has not identified a recent change tied to the outage's start.