Summary of impact: Between 08:30 and 11:30 UTC on 06 Apr 2018, a subset of Azure Active Directory customers in East Asia and Europe may have experienced difficulties when attempting to authenticate into resources which are dependent on Azure Active Directory.
Downstream impact was reported by a number of Azure services, including Office 365, for which customers may have experienced: Backup: failures for the registration of new containers and backup/restore operations. Storsimple: new device registration failures and Storsimple management/communication failures. Azure Bot Service: bots reporting as unresponsive. Visual Studio Teams Services: higher execution times and failures while getting AAD tokens in multiple regions. Media Services: authentication failures. Azure Site Recovery: new registrations and VM replications may also have failed.
Preliminary root cause: Engineers determined that instances of a backend service responsible for processing authentication requests became unhealthy preventing requests from completing.
Mitigation: Engineers performed a recovery of the impacted backend service.
Microsoft engineers will continue to investigate to establish the full root cause and a full root cause analysis should be available in 72 hours.