Microsoft Confirms Windows 11 25H2 UI Features Broken Along With 24H2 Following Update

Microsoft confirmed a critical timing/race-condition bug in Windows 11 (24H2 and 25H2) triggered by cumulative updates that prevents XAML-dependent packages (e.g., MicrosoftWindows.Client.CBS, Microsoft.UI.Xaml.CBS) from registering before the Shell initializes, causing Explorer.exe, ShellHost, Start menu, and other UI components to crash or hang—resulting in black screens or non-functional desktops, with disproportionate impact on enterprise VDI and non-persistent environments; Microsoft is developing a fix while recommending manual package registration via PowerShell or a synchronous logon script as interim mitigations.