Microsoft 365 Services Crumble Under User Authentication Crisis

Microsoft's Outlook and other Microsoft 365 services experienced a widespread outage on Monday, affecting thousands of users. The problems began around late morning, with users reporting authentication errors, delayed or failed emails, and issues accessing other services such as OneDrive for Business, SharePoint, Teams, and Microsoft Purview. Downdetector reported over 6,000 complaints about Outlook during the outage.

The root cause of the issue was identified as a problem with a core authentication configuration, which is responsible for recognizing and authenticating users across multiple services. Microsoft stated that restarting this malfunctioning infrastructure would resolve the issue, but warned that users could still experience delays due to a backlog of emails in the system.