Microsoft investigated an issue where Multi-Factor Authentication (MFA) prevented users from accessing some Microsoft 365 apps, causing a service outage. The company redirected traffic to improve availability and later confirmed that service had been restored, though the exact cause remains unknown. Downdetector reported related outages in the U.S. This follows a similar incident in late 2024 affecting Exchange Online and Microsoft Teams calendar functionality, highlighting ongoing challenges with service reliability for Microsoft's cloud-based platforms.

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