Were you unable to login to your Azure Active Directory or Office 365 accounts yesterday? The reason was a global Multi-Factor Authentication issue. It has since been fixed.
The Microsoft Office 365 status page reported that users who were hit by this were also unable to do self-service password resets. In other words, if you requested a new password through two-step authentication and tried having the service send you a message through your phone, nothing happened.
Examining the Office 365 status page, it was revealed that Office 365 MFA services started to become unavailable at 4:39 AM UTC. Microsoft Azure status page revealed that affected users may have had problems logging in to Azure Active directory and similar services when the problems with MFA began.
Around noon on Monday, Microsoft Azure engineers reported having deployed a hotfix which needed a bit of time to take effect, particularly in Europe and the Asia-Pacific region. According to them, the hotfix was a success, and they noticed a reduction in the number of authentication errors because of it.
The Azure status page noted the engineers continued to be working on the problem. Allegedly, they were exploring additional workstreams and how Azure customers in the said region were affected so the issue could be fully mitigated.
As it appears, the MFA issues seem to be over. The Azure page claims the services are running normally, and the Office 365 page notes that their team is working on preventing future instances of the problem. Microsoft is still searching for the root cause of the problem.