Since October 18, 2019, multifactor authentication for Azure and Office 365 appears to be disrupted. At least customers in North America are affected.
Admins who are unable to access the admin center can find updates on the MFA outage MO193431 through https://t.co/4yJVZgAm9A.
— Microsoft 365 Status (@MSFT365Status) October 18, 2019
The Microsoft 365 Service Health Status page shows since that day the text below:
Title: Unable to access Microsoft 365 services
User Impact: Users may be unable to sign in to Microsoft 365 services. More info: Users may not receive authentication requests via phone call, SMS or within their authenticator app.
Current status: Our services remain healthy, and we’ve confirmed via continuous service monitoring that all of the previously affected scenarios are working as expected. Additionally, we’re progressing through our investigation to isolate the underlying problem.
Scope of impact: This issue could have affected any of your users located in North America if they leverage MFA to access Microsoft 365 services. Start time: Friday, October 18, 2019, at 1:30 PM UTC
Next update by: Monday, October 21, 2019, at 7:30 PM UTC
It seems that this is a major issue that causes this service disruption – it might be the 3rd incident with MFA within this year.