28-09-2021 04:23:00 PM (BST)
Microsoft Reference : MO287933
Issue Status: RESOLVED
Issue Description: On-premises users who utilize Multi-Factor Authentication (MFA) may be unable to access Microsoft 365 services
Scope of impact: This issue specifically impacted customers who use on-premises Multi-Factor Authentication (MFA) servers to connect to Active Directory Federation Services (ADFS) or Network Policy Server (NPS). Cloud Authentication was not impacted.
Final Update – 29/09/2021 12:59:00 PM: Microsoft performed scale up activities on the underlying infrastructure to mitigate the issue and have also confirmed with impacted customers that the issue is now resolved for them.