Microsoft confirms Windows 11 KB5079473 can break Microsoft sign-ins

Microsoft has confirmed a new known issue affecting some PCs after the installation of the March 2026 Windows 11 cumulative update KB5079473. The company says some users may be unable to sign in with a Microsoft account, in several apps, after the update is installed. Microsoft’s support page lists KB5079473 for Windows 11 24H2 and 25H2 as OS Builds 26100.8037 and 26200.8037, released on March 10, 2026.

Third-party media reported on March 20, 2026, that Microsoft had updated its Windows release health information to acknowledge the bug. According to that report, the issue can affect Microsoft Teams Free, OneDrive, Microsoft Edge, Excel, Word, and Microsoft 365 Copilot when those apps require a Microsoft account sign-in.

The error can appear even when a PC is online

Microsoft says affected devices may show an error message saying the user needs the internet, even when the PC is connected. External media quoted Microsoft as saying sign-in attempts can display text similar to: “You’ll need the Internet for this. It doesn’t look like you’re connected to the Internet.” The report also says Microsoft believes the problem is tied to a specific network connectivity state triggered after the update is installed.

Microsoft also says the issue is limited to sign-in operations involving Microsoft accounts. According to the same release health update cited by third-party media, organizations using Entra ID for app authentication are not affected by this particular problem.

Microsoft’s current workaround is a restart while connected

While it works on a permanent fix, Microsoft says affected users should restart the device while it is connected to the internet. The company says that itcan repair the connectivity state and prevent the issue from recurring. Microsoft also warns that restarting without an active internet connection may return the device to the same faulty state.

KB5079473 was released as part of Microsoft’s March Patch Tuesday rollout for supported Windows 11 versions. Microsoft’s support documentation confirms the update and build numbers, while the newly acknowledged sign-in issue adds to a growing list of post-installation complaints surrounding this month’s release