Windows 11 KB5085516 Emergency Update Fixes Microsoft Account Login Failures

Microsoft’s March Patch Tuesday update for Windows 11 has led to widespread issues, prompting the company to release an emergency out-of-band fix. The problems primarily affected users trying to sign in to Microsoft services, disrupting access across multiple apps.

Sign-in bug blocks access to key Microsoft apps

Shortly after the update rolled out, users began reporting sign-in failures across several Microsoft services. The issue triggered a misleading “no Internet connection” error, even on devices with fully working connectivity.

This bug prevented users from accessing essential apps, including Microsoft Teams, OneDrive, Copilot, Excel, Word, and Edge. The problem appeared tied specifically to Microsoft Account authentication, as enterprise users with Microsoft Entra ID accounts were not affected.

Microsoft pushes out-of-band update KB5085516

As Neowin writes, Microsoft released update KB5085516 as an out-of-band fix for affected systems. The update resolves the authentication issue and restores normal access to Microsoft services.

The fix is now available in the following Windows 11 builds:

• 26200.8039 for Windows 11 25H2
• 26100.8039 for Windows 11 24H2

Users can install the update manually through the Optional updates section in Windows Update.

Patch Tuesday update causes additional installation problems

The sign-in bug was not the only issue tied to the March update. Some users also reported failures when installing the update KB5079473, with crashes and installation errors preventing completion.

These issues add to growing concerns around update stability, especially when critical services like authentication are affected.

Microsoft has not shared full details on what caused the problems, but moved quickly to address the most disruptive bug with the out-of-band release.