Security News > 2021 > March > Microsoft explains the cause of yesterday's massive service outage
Microsoft has shed some light on the root cause behind yesterday's massive Azure authentication outage that affected multiple Microsoft services and blocked users from logging into their accounts.
This issue prevented users from authenticating to Microsoft 365, Exchange Online, Microsoft Teams, or any other service relying on Azure AD. "Between 19:00 UTC on March 15, 2021, and 09:25 UTC on March 16, 2021 customers may have encountered errors performing authentication operations for any Microsoft and third-party applications that depend on Azure Active Directory for authentication," Microsoft explained today in a preliminary root cause analysis report.
Microsoft engineers rolled back the key metadata to the state before the worldwide service outage started to mitigate the issue.
While the outage impact was largely mitigated after rolling back the key changes, Microsoft is still working on bringing back up Intune and Microsoft Managed Desktop.
In September, Microsoft customers experiencing another massive worldwide outage showing "Transient" errors that knocked down Office 365 and related services, including Microsoft Teams, Office.com, Power Platform, and Dynamics365.
As Microsoft explained at the time, that outage was caused by an Azure AD service update that mistakenly hit the production environment.