azure west us outage: a repair job cut a datacenter off the wan

what happened

• Microsoft's post-incident review (tracking ID ZJV6-SGG) gives an impact window of 14:44–19:41 UTC on 23 July 2026 for connectivity failures and higher latency reaching resources in West US.[1]
• Only traffic entering or leaving the region was affected; traffic staying inside West US was not.[1]
• A break-fix repair on one optical device was processed automatically, and a defect in the blast-radius analysis widened it to all optical devices leaving one datacenter, cutting that datacenter off from Microsoft's WAN.[1]
• The safety check validated devices one at a time rather than their combined effect, and the automated rollback failed because it relied on the same disrupted connectivity.[1]
• Manual rollback started at 17:45 UTC and succeeded on all affected devices at 18:26 UTC.[1]
• Affected Azure services included App Service, AKS, Cosmos DB, ExpressRoute, Azure Firewall, VPN Gateway and Azure Virtual Desktop; Microsoft 365 impact was tracked as MO1437424.[1,2]
• BleepingComputer reported Microsoft 365 services including OneDrive, SharePoint Online and Teams were disrupted.[2]