Microsoft’s multi-factor authentication (MFA) for Azure and Microsoft 365 (M365) was offline for four hours during Monday’s busy start for European subscribers.

“Multi-Factor Authentication (MFA) may prevent users from accessing some Microsoft 365 (M365) and Azure Apps,” the software giant said referencing an OP978247 incident report.

“User impact: Users may be unable to access some Microsoft 365 and Azure Apps when authenticating with MFA. We’re reviewing service diagnostic data to help us determine the full scope of impact and which exact services are affected.”

Redmond first reported problems at 1033 UTC and sysadmins in Norway, Spain, the Netherlands, and the UK all reported sign-on issues. Around four hours later, Microsoft said the outage was mostly fixed, and said those affected were mostly confined to Western Europe, although users in Chile and the US are still reporting issues.

“We’ve confirmed by monitoring service telemetry that redirecting the affected traffic has returned the service to normal health,” it said in an update. “We’ve begun a period of extended monitoring to ensure this continues, while we continue to investigate the cause of the impact.”

This is Azure’s second outage in a week, following a disruption in the East US 2 region. The earlier incident was attributed to a networking service configuration change, leading to intermittent errors and connectivity issues for various services.

We’ve asked Microsoft for details on the incident and will update you as more information comes in. ®