Microsoft's January security update, released on January 13, 2026, has caused connection and authentication failures for users of Azure Virtual Desktop and Windows 365, particularly affecting those using the Windows App. The update has resulted in credential prompt failures during Remote Desktop connections across all supported Windows versions, from Enterprise LTSC 2016 to Windows 11 25H2, as well as Windows Servers from 2019 to 2025. Microsoft is investigating the issue and plans to release an out-of-band update soon. Users have been advised to either uninstall the update or use the Remote Desktop Client or the Windows App web client as workarounds. Reports indicate persistent issues, including an "Unable to Authenticate" error when attempting to connect via the Windows App. Microsoft has also made a Known Issue Rollback available to address these credential problems.