Authentication errors across multiple Microsoft or Azure services - Mitigated (Tracking ID SM79-F88)
Summary of incident: Starting at approximately 21:25 UTC on September 28, 2020, customers may have encountered errors when attempting to authenticate to Microsoft services including Microsoft 365, Azure, Dynamics 365 or custom applications that rely on AAD for authentication.
Users who were not already authenticated to the cloud services using Azure AD would have seen multiple authentication request failures. Impact was primarily in the Americas based on the issue being exacerbated by load, but users in other regions may also have experienced some impact. Users that had previously authenticated prior to the issue may not have experienced any noticeable effect. More details about the impact will be provided in the PIR.
We have identified the preliminary root cause and the extended impact as a combination of three separate and unrelated issues.
A code defect in a service update.
A tooling error