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Servers failing when brought back online have kept Outlook down for most of a workday, affecting millions of users.
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What a day to hit up MSFT HQ for the first time. I didn’t know Outlook had an outage when posting this, and definitely not that it would be the largest-ever email-related outage since 1997 (when a reply-all outage took down Microsoft’s internal email for ~2 days.)Read original on X
Microsoft Outlook is down. Microsoft 365 issues are cutting people off from their email, as well as Microsoft Teams, SharePoint Online, and Microsoft 365 CopilotRead original on X
I am hearing that Microsoft's Outlook outage is down to some kind of rollout that caused servers to spike CPU usage, causing racks to go into maintenance mode and creating cascading failuresRead original on X
Holy cow, there’s a massive Microsoft outage going on. Outlook .com is down, globally, as I understand. Microsoft employees cannot send/receive email as well (plus everyone else using M365) This is very bad given how important email is for comms Postmortem will interestingRead original on X
Outlook has been broken for most of a workday, and Microsoft can't just switch it back on. Every phone and laptop that's been retrying email since this morning would hit the servers in the same second and knock them right back over. That's pretty much how it broke in the first place. Every Exchange server gets watched by an automated health check, and if it fails, it gets yanked out of rotation so nobody's email lands on a broken machine. With one bad server, that's great design. Today a core process on a whole bunch of them started choking at once (Tom Warren reports a rollout spiked CPU and pushed racks into maintenance mode), and Microsoft's own update says servers were failing those health checks and dropping out. So follow one person's inbox. Their server gets pulled, but their…Read original on X
Madness - 12 hours into the outage. Microsoft is posting regular updates but they have not figured out what is causing servers to die when brought back online From their updates it sounds like it’s a thundering herd + some other weird issue they’ve yet to pinpointRead original on X
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