Microsoft 365 is down. The latest clue: the part that checks server health.
SummaryOutlook, Exchange Online and Teams access broke for users on Nov. 12. Microsoft says servers kept failing automated health checks, and the problem may be the component that processes those checks.
· MODEL Editors · 1 min read
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What broke. At 9:54 a.m. PT on Nov. 12, Microsoft's @MSFT365Status (opens in a new tab) account said it was investigating problems reaching Exchange Online mailboxes "through multiple connection methods in the Americas." About 13 minutes later it said the issue may affect Microsoft 365 connectivity for users in any region. Microsoft's status page (opens in a new tab) lists Exchange Online, Microsoft Teams, SharePoint Online, Microsoft Copilot 365 and Microsoft Defender XDR as potentially affected.
How big. Nearly 130,000 people reported Outlook problems on Downdetector just after 1 p.m. ET, AP reported (opens in a new tab). Microsoft is posting updates publicly because some admins can't reach the Microsoft 365 admin center.
What Microsoft says is going on. The extra load isn't coming from more traffic, Microsoft said. It comes from a large number of servers going offline unexpectedly, which pushes their work onto the servers that are left. Those servers were failing automated health checks. Microsoft paused all deployments and configuration changes, moved traffic off the affected infrastructure, restarted affected servers and began testing a configuration change.
The punchline. In its 12:19 p.m. PT update, Microsoft said it hasn't found a recent change that lines up with when the problem started. It also said "the failed health checks may originate from a specific component that's responsible for processing server health." In other words, the checkup itself may be what's sick. Microsoft said it has taken steps to stop more servers from being affected while it returns the others to service.
Status. As of 12:40 p.m. PT, Microsoft hadn't said the issue was resolved. A separate Teams issue in North America earlier that morning (TM1550488) was marked fully resolved at 9:09 a.m. PT. Updates are posted under EX1550543 and MO1550821.
Disclosure: Not tested by MODEL. Not sponsored. No affiliate links.
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