Windows 11 KB5079473 Breaks Microsoft Account Sign-Ins Across Microsoft Apps

Microsoft confirmed that the Windows 11 cumulative update KB5079473 is causing Microsoft account sign-in failures in several Microsoft applications, including Teams, OneDrive, Edge, Excel, Word, and Microsoft 365 Copilot. Affected users are shown a misleading message stating that the device is not connected to the Internet, even when connectivity is working, preventing normal sign-in activity across those services.

The issue has been linked to a specific network connectivity state and appears to affect Windows 11 systems on versions 24H2 and 25H2 that use Microsoft accounts, while organizations authenticating with Entra ID are not impacted. Microsoft said it is developing a permanent fix and, in the meantime, recommends restarting affected PCs while they remain connected to the Internet, noting that the problem can return if a device is rebooted without an active connection.