Microsoft Issues Quick Fix KB5085516 for Windows 11 After KB5079473 Disrupts Microsoft Account Sign‑In Across Popular Apps

Microsoft has rolled out a new cumulative update for Windows 11—KB5085516—following a wave of complaints that the earlier update, KB5079473, broke Microsoft account sign‑in for several widely used applications. The latest patch restores the authentication flow, clears the error messages that appeared for users, and includes a handful of additional stability improvements.

What Went Wrong with KB5079473?

When Microsoft released KB5079473 on March 12, 2026, the update was intended to tighten security around the Windows Credential Manager and improve network handling for modern apps. However, a misconfiguration in the update’s authentication module caused the Windows 11 sign‑in token to be rejected by the Microsoft identity platform in certain scenarios.

The problem manifested most noticeably in apps that rely on the built‑in Microsoft account integration, such as:

Microsoft Teams
OneDrive
Outlook for Windows
Microsoft Store
Edge browser sync

Users reported error messages like “We can’t sign you in right now” or “Your account could not be verified.” In many cases, the apps would repeatedly prompt for credentials, only to reject them each time. The issue was not limited to a single device; it appeared on both desktop PCs and laptops running the latest Windows 11 build (22H2).

Technical analysis from the Windows Insider community indicated that the update unintentionally altered the WebAuthn handshake, causing a mismatch between the client and Microsoft’s authentication servers. Because the problem was tied to a core component, rolling back the update was not a straightforward solution for most users.

How KB5085516 Restores Sign‑In Functionality

Microsoft’s response came quickly. Within a week of the complaints, the company released KB5085516, a targeted fix that restores the original authentication flow while preserving the security enhancements introduced in KB5079473. The new update does three things:

Reverts the faulty WebAuthn changes: The patch removes the erroneous registry modifications that broke the token exchange.
Re‑enables Microsoft account token caching: This ensures that apps can retrieve a valid token without repeatedly prompting the user.
Includes minor bug‑fixes: Additional tweaks address unrelated performance regressions reported after the March update.

According to Microsoft’s official release notes, the fix has been tested on a broad range of hardware configurations, from low‑end Surface devices to high‑performance gaming rigs. Early feedback suggests that the sign‑in issue is resolved for the majority of affected applications.

Steps to Install KB5085516 and Verify the Fix

If you’re still seeing sign‑in problems after installing the March update, follow these steps to get the new patch and confirm that your Microsoft account works across apps:

Open Settings: Press Win + I or click the Start menu and select the gear icon.
Navigate to Windows Update: Choose Update & Security → Windows Update.
Check for updates: Click Check for updates. Windows should detect KB5085516 and list it under “Optional updates” if it doesn’t appear automatically.
Install the update: Select the update and click Download and install. The process may take several minutes and will likely require a restart.
Verify the fix: After reboot, open one of the previously affected apps (e.g., Teams). Sign in with your Microsoft