--- title: Microsoft blames massive Microsoft 365 outage on... description: A bug in Microsoft's automated network maintenance request system caused a major outage on July 23, 2026, affecting Microsoft 365 and Azure services. The bug... canonical: https://daily.dev/posts/microsoft-blames-massive-microsoft-365-outage-on-maintenance-bug-6v6fhc5ky twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Microsoft blames massive Microsoft 365 outage on maintenance bug | daily.dev og:description: A bug in Microsoft's automated network maintenance request system caused a major outage on July 23, 2026, affecting Microsoft 365 and Azure services. The bug... og:url: https://daily.dev/posts/microsoft-blames-massive-microsoft-365-outage-on-maintenance-bug-6v6fhc5ky og:image: https://api.daily.dev/og/posts/6v6FhC5Ky.png og:image:alt: Microsoft blames massive Microsoft 365 outage on maintenance bug og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Microsoft blames massive Microsoft 365 outage on maintenance bug **[BleepingComputer](https://daily.dev/sources/bleepingcomputer)** · 4 min read · 1 upvotes · 0 comments ## Summary A bug in Microsoft's automated network maintenance request system caused a major outage on July 23, 2026, affecting Microsoft 365 and Azure services. The bug incorrectly marked additional network devices as part of a maintenance event, causing IP routes to be removed from more devices than intended in the West US Azure region. This disrupted traffic between the West US datacenter and Microsoft's wide-area network, impacting SharePoint, OneDrive, Teams, Power Automate, Copilot Chat, and dozens of Azure services. Microsoft engineers traced the issue to recent maintenance activity, initiated a rollback at 1:45 PM ET, and fully restored all services by 3:41 PM ET. Microsoft is conducting a full internal review of its safety checks and automated maintenance processes, with a final Post Incident Review expected within 14 days. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What caused the Microsoft 365 and Azure outage on July 23 in the West US region? A bug in Microsoft's automated network maintenance request system incorrectly marked additional network devices as part of a routine maintenance event, causing IP routes to be removed from more devices than intended between the West US datacenter and the wide-area network. This disrupted traffic entering or leaving the region while traffic staying entirely within the region remained unaffected. _Track root-cause postmortems like this one on daily.dev to spot recurring cloud reliability risks._ ### Which Microsoft 365 and Azure services were affected by the July 23 West US outage? Affected Microsoft 365 services included OneDrive, SharePoint Online, Teams, the Admin Center, Power Automate, Copilot Chat, and Loop, while impacted Azure services included App Service, Application Gateway, Cosmos DB, Kubernetes Service, Virtual Desktop, ExpressRoute, Microsoft Graph, Sentinel, and VPN Gateway, among others. SharePoint accounted for 78% of Downdetector reports. _Engineers assessing cloud dependency risk follow incident breakdowns like this on daily.dev._ ### How long did it take Microsoft to fix the July 23 Microsoft 365 outage? Microsoft began investigating at 10:44 AM ET when the outage started, initiated a rollback of the maintenance change at 1:45 PM ET, completed the rollback at 2:26 PM ET, and confirmed all affected services had fully recovered by 3:41 PM ET. A final Post Incident Review is expected within 14 days of the incident. _Teams planning disaster recovery around Microsoft 365 uptime follow incident timelines like this on daily.dev._ ## Similar posts on daily.dev - [Microsoft 365 hit by outage, preventing access to emails and files](https://daily.dev/posts/microsoft-365-hit-by-outage-preventing-access-to-emails-and-files-irywo2f8j) · TechCrunch · 0 upvotes · 0 comments - [Microsoft confirms outage affecting search in Microsoft 365 apps](https://daily.dev/posts/microsoft-confirms-outage-affecting-search-in-microsoft-365-apps-kbc6i6lst) · BleepingComputer · 0 upvotes · 0 comments - [Quick thoughts on Azure Regional Outage from July 23, ’26](https://daily.dev/posts/quick-thoughts-on-azure-regional-outage-from-july-23-26-9uwfpbxa9) · Surfing Complexity · 0 upvotes · 0 comments - [Azure power wobble knocks Windows Update offline](https://daily.dev/posts/azure-power-wobble-knocks-windows-update-offline-fpaigpb8a) · The Register · 0 upvotes · 0 comments --- Tags: [#microsoft](https://daily.dev/tags/microsoft), [#azure](https://daily.dev/tags/azure), [#networking](https://daily.dev/tags/networking) [View this post on daily.dev](https://daily.dev/posts/microsoft-blames-massive-microsoft-365-outage-on-maintenance-bug-6v6fhc5ky) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Microsoft blames massive Microsoft 365 outage on maintenance bug","url":"https://daily.dev/posts/microsoft-blames-massive-microsoft-365-outage-on-maintenance-bug-6v6fhc5ky","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/microsoft-blames-massive-microsoft-365-outage-on-maintenance-bug-6v6fhc5ky"},"datePublished":"2026-07-24T15:45:37.706Z","dateModified":"2026-09-13T20:42:45.017Z","description":"A bug in Microsoft's automated network maintenance request system caused a major outage on July 23, 2026, affecting Microsoft 365 and Azure services. 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