The unscheduled Windows 11 KB5085516 update resolves a Microsoft account login error that appeared after installing update KB5079473 on devices running Windows 11 versions 24H2 and 25H2.

Key Information About the Update

Update KB5085516 was released on March 21, 2026, for Windows 11 versions 24H2 and 25H2. After installing this patch, systems are updated to builds 26100.8039 and 26200.8039. The main purpose of this update is to fix a bug that prevented users from logging into their Microsoft accounts.

Causes of the Issue

The login error occurred after installing the cumulative update KB5079473, which was released on March 10, 2026. This bug prevented some users from signing into apps using their Microsoft accounts, even if they had an active internet connection. In some cases, the system incorrectly displayed a message about no internet connection and blocked access to Microsoft services and apps, including Microsoft Teams Free and OneDrive.

The problem only affected logins using Microsoft accounts. Organizations using Microsoft Entra ID for app authentication did not experience this issue.

Update Contents and Distribution

KB5085516 also includes quality improvements from the previous KB5079473 update, but its main goal is to fix the login error that appeared after the March 2026 updates or later. This is a targeted patch, not a major feature update.

The update is distributed through Windows Update for devices that already have KB5079473 installed, and it is also available for manual download from the Microsoft Update Catalog. Computers with the “Get the latest updates as soon as they’re available” option enabled receive the patch automatically. Other users can install the update manually via “Settings” > “Windows Update.”

Additional Information

The Microsoft support page states that no known issues have been identified with update KB5085516. This allows Windows 11 users who encountered Microsoft account login errors after the March update to use the official solution to resolve the problem.