Two related incidents hit Microsoft 365 on 1 October 2026, starting at 17:28 UTC and lasting 1h 27m. SharePoint Online and OneDrive both threw latency and 503 service unavailable errors, and the fault sat with Microsoft's infrastructure, not yours.
Started
17:28 UTC
Duration
Lasted 1h 27m
Source
IsDown
Next time
Microsoft 365 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: SharePoint Online
What happened?
Microsoft logged two separate incidents on 1 October 2026, both starting at 17:28 UTC and both running 1h 27m. The first affected SharePoint Online, where users saw latency and 503 service unavailable errors when trying to reach sites. The second hit Microsoft OneDrive content, with the same symptom pattern: delays, navigation errors, and 503s. Microsoft's first update for each incident said it was investigating a potential issue and checking for impact, with a promise of an update within the hour. A second update followed for each, roughly 25 to 30 minutes later, saying Microsoft was using its own service-side telemetry to understand the issue and find a remediation path, and confirming that affected organisations would see the latency and 503 errors described. Both incidents named a next update time of 19:00 UTC on 1 October. The record shows four updates total across the two incidents, and no further updates beyond those shown, meaning the resolution itself was not separately detailed in what's on the record. No user reports were filed during this window. Microsoft's status page is the only source for what happened here, and it only ever describes its own view of impact to "your organization" in generic terms, not a verified account of what any specific tenant experienced. Over the past 90 days, Microsoft 365 has logged 46 incidents with a median duration of 9 hours 25 minutes, and all time its average is 7.7 incidents a month. Against that history, 1h 27m is short.
Learning
When SharePoint Online and OneDrive throw 503s like this, the fault sits inside Microsoft's own serving layer, something no amount of watching your own application endpoints would reveal, because your endpoints are calling out to Microsoft, not standing in for it. If your monitoring only checks your own product, it can stay green while your users still get 503s from Microsoft's side and errors bubble up into your product regardless. Two different layers are failing independently here: your application layer, which may be fine, and Microsoft's storage and collaboration layer, which was not. That is the shape to recognise: your own checks pass, your users still complain, and the actual fault is one hop upstream, at a provider you don't control and can't patch. Microsoft's own telemetry-based updates are useful but they are Microsoft describing Microsoft, not an independent confirmation of what you saw. Your monitoring covers your half, UptimeRobot now watches the provider's half too, so next time you know which side broke without guessing.
