Microsoft Emergency Out-of-Band Update for Windows 11 to Fix Microsoft Account Sign-In Failure

Microsoft released an out-of-band cumulative update KB5085516 (OS builds 26200.8039 and 26100.8039) on March 21, 2026 to fix a critical sign-in regression caused by the March 10 update KB5079473 that prevented Microsoft account authentication (reporting a “no Internet” error), and the release also includes refreshed AI components and a servicing stack update KB5083532 for Windows 11 24H2; the update is being deployed automatically and Microsoft reports no known issues at publication.