A bug in Microsoft’s automated network maintenance system caused IP routes to be removed from devices, isolating a West US Azure datacenter and disabling Teams, SharePoint, OneDrive and other services for nearly five hours.
A glitch in Microsoft’s automated Azure network maintenance routine unintentionally stripped IP routes from a West US datacenter, leaving critical Microsoft 365 services—including Teams, SharePoint, and OneDrive—offline for almost five hours.
What Went Wrong
During a scheduled maintenance window, the system that normally updates routing tables mistakenly issued a command to delete active routes. The error isolated the datacenter from the broader Microsoft network, causing a cascade of service failures across the Microsoft 365 suite.
Impact on Users
Enterprise and consumer users reported being unable to join Teams meetings, access shared files on SharePoint, or sync documents via OneDrive. The outage also affected Outlook web access and other cloud‑based collaboration tools that rely on the same Azure backbone.
The disruption lasted roughly four hours and fifty minutes, with Microsoft restoring connectivity after engineers manually re‑established the missing routes and verified service health across affected regions.
Microsoft’s Response
Microsoft issued a post‑mortem stating that the bug originated from a recent update to its automated maintenance scripts. The company pledged to add additional safeguards to prevent route‑deletion commands from executing without explicit validation.
- Review and harden automated network maintenance procedures
- Implement redundant routing checks before changes are applied
- Enhance monitoring to detect route loss instantly
We are deeply sorry for the inconvenience caused and are taking immediate steps to ensure this does not happen again, said a Microsoft spokesperson.
The incident underscores the complexity of cloud infrastructure and the ripple effect a single routing error can have on globally used productivity tools.