On September 28 and September 29 this week, a number of Microsoft customers worldwide were impacted by a cascading series of problems resulting in many being unable to access their Microsoft apps and services. On October 1, Microsoft posted its post-mortem about the outages, outlining what happened and next steps it plans to take to head this kind of issue off in the future.
Starting around 5:30 p.m. ET on Monday, September 28, customers began reporting they couldn’t sign into Microsoft and third-party applications which used Azure Active Directory (Azure AD) for authentication. (Yes, this means Office 365 and other Microsoft cloud services.) Those who were already signed in were less likely to have had issues. According to Microsoft’s report, users in the Americas and Australia were likely to be impacted more than those in Europe and Asia.
Microsoft acknowledged it was a service update targeting