Microsoft MFA outage blocking access to Microsoft 365 apps

​Microsoft is investigating an ongoing Multi-Factor Authentication (MFA) outage that is blocking customers from accessing Microsoft 365 Office apps.

Some affected Microsoft 365 users have also reported that MFA registration and reset are not working.

“Users may be unable to access some Microsoft 365 Apps when authenticating with MFA,” Microsoft said in an incident alert published in the admin center. “We’re re-directing traffic to alternate healthy infrastructure while we continue to investigate the root cause of impact.”

The company added that the incident only impacts users who use MFA for authentication in Microsoft 365 Office apps.

According to another admin center message, the company is also investigating reports that Microsoft 365 applications may unexpectedly crash on Windows Server 2016 devices.

“We’re reviewing service monitoring telemetry to isolate the root cause and develop a remediation plan,” Redmond says. “Impact is specific to some users who are served through the affected infrastructure.”

Last month, Microsoft announced it was investigating a known issue that triggers “Product Deactivated” errors for customers using Microsoft 365 Office apps. One week earlier, another outage took down Office web apps and the Microsoft 365 admin center.

In November, A worldwide Microsoft 365 outage also impacted multiple services and features, including Microsoft Teams, Exchange Online, SharePoint Online, OneDrive, Purview, Copilot, and Outlook Web and Desktop.

Update: January 13, 05:51 EST: Microsoft says service availability has been restored, and the issue is resolved.

“We’ve identified that a section of infrastructure responsible for MFA operations unexpectedly became unresponsive,” the company says in the admin center.

“We’ve completed an extended period of monitoring in which the service health has remained stable and are declaring this incident as resolved. Impact was specific to users are authenticating to our M365 Apps using MFA via infrastructure in Western Europe.”