If you rely on Claude's Microsoft 365 connector, mail, calendar, SharePoint and Teams chat requests through it have been failing since 17:52 UTC. The fault sits with Microsoft, not with Claude itself, and the incident is still open as updates continue.
Started
17:52 UTC
Duration
Ongoing
Source
IsDown
Next time
Anthropic is degraded. Is your product working?
An incident on their side does not always mean an outage on yours, and the only way to know is to already be watching your own endpoints. Set that up in under a minute and you will be notified the next time your own site is affected. And there will be a next time.
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Affected components: claude.ai
What happened?
Anthropic's status page opened this incident at 17:52 UTC, reporting elevated errors and slow responses on the Microsoft 365 connector, with mail, SharePoint, Teams chat and calendar requests failing and new connections sometimes unable to complete. By 18:34 Anthropic had identified the cause as an issue with an upstream provider, saying mail, calendar and search tools were failing for most requests. At 20:28 the company confirmed Claude for Outlook was also affected, with mail and calendar actions failing and some users unable to open the add-in at all. The 21:18 update said the upstream provider was restarting affected servers, with the connector and Claude for Outlook still down. At 22:23, Anthropic named the cause directly: a Microsoft 365 service incident, and pointed users to Microsoft's own status page at status.cloud.microsoft to follow progress there. Only one component is listed as affected on Anthropic's page, claude.ai, which covers the connector in question. No resolution has been posted as of the 22:23 update, so the incident remains open on Anthropic's own clock. No user reports were filed during this window, so the account here rests entirely on Anthropic's five published updates. Anthropic has logged 44 incidents in the past 90 days with a median duration of 45 minutes, which this one has already well exceeded given how long it has run without resolution.
Learning
This outage shows a failure one layer removed from Anthropic itself: Claude's own infrastructure was working, but a connector depending on Microsoft 365 broke because Microsoft's servers broke, something no amount of watching claude.ai's homepage or API would have caught. If you only monitor your own endpoints, you would have seen your product start failing specific actions, mail, calendar, search, with no obvious reason on your side, and no indication that the real fault sat two providers upstream, at Microsoft. Anthropic's own updates had to chase the explanation across 17:52, 18:34, 20:28 and 21:18 before naming Microsoft directly at 22:23, nearly five hours in. That lag between symptom and named cause is normal for incidents that cross vendor boundaries, and it means your own dashboards will look fine while real requests still fail for your users. Your monitoring covers your half, UptimeRobot now watches the provider's half too, so next time you know which side broke without guessing.
