Microsoft: Windows 11 bug crashes Explorer and Start Menu

Update December 03, 08:39 EST: Microsoft has updated the support document to include Windows 11 25H2 to the list of affected OS versions. We have revised the title and story accordingly.

Microsoft warns that a critical Windows 11 bug causes the File Explorer, the Start Menu, and other key system components to crash when provisioning systems with cumulative updates released since July 2025.

This bug is triggered on "first time user logon after a cumulative update was applied" and on all logins for users on non-persistent operating system installations (such as virtual desktop infrastructure environments), where app packages must reinstall each session. On impacted systems, it causes issues for multiple essential Windows 11 shell components when XAML dependency packages fail to register properly after updates.

As Microsoft explained in a recent support document, applications that depend on XAML packages (specifically MicrosoftWindows.Client.CBS, Microsoft.UI.Xaml.CBS, and MicrosoftWindows.Client.Core) aren't registering in time after an update is installed, a timing issue that cascades through the system, preventing critical interface components from initializing properly.

This causes shell components such as Explorer.exe, StartMenuExperienceHost, and ShellHost.exe to crash with visible errors or fail silently, leaving users with partially functional systems that cannot display various navigation tools.

Affected users can experience a wide range of problems, including Start menu crashes (often accompanied by critical error messages), missing taskbars even when Explorer.exe is running, the core ShellHost (Shell Infrastructure Host or Windows Shell Experience Host) system process crashing, and the Settings app silently failing to launch.

"After provisioning a PC with a Windows 11, version 24H2 or a Windows 11, version 25H2 monthly cumulative update released on or after July 2025 (such as KB5062553 or KB5065789), XAML-dependent modern apps such as Explorer, the Start menu, SystemSettings, Taskbar and Windows Search might experience difficulties," Microsoft said.

"The applications have dependency on XAML packages that are not registering in time after installing the update. We are working on a resolution and will provide more information when it is available."

Temporary workaround available

Microsoft stated it's developing a resolution but hasn't provided a timeline for the fix. While Microsoft continues to work on a permanent fix, it has provided PowerShell commands to manually register the missing packages.

Affected users must run these three Add-AppxPackage commands targeting each affected XAML package, then restart the system to restore functionality:

Add-AppxPackage -Register -Path 'C:\Windows\SystemApps\MicrosoftWindows.Client.CBS_cw5n1h2txyewy\appxmanifest.xml' -DisableDevelopmentMode
Add-AppxPackage -Register -Path 'C:\Windows\SystemApps\Microsoft.UI.Xaml.CBS_8wekyb3d8bbwe\appxmanifest.xml' -DisableDevelopmentMode
Add-AppxPackage -Register -Path 'C:\Windows\SystemApps\MicrosoftWindows.Client.Core_cw5n1h2txyewy\appxmanifest.xml' -DisableDevelopmentMode 

However, the bug particularly impacts organizations managing non-persistent enterprise environments using virtual desktop infrastructure, where employees must re-provision applications at each login.

For them, Microsoft recommends running this logon script on non-persistent OS installations that will execute before Explorer launches. The batch file wrapper ensures required packages are fully provisioned before the desktop environment loads, preventing the timing race condition.

Last week, Nvidia also released a GeForce Hotfix Display Driver to address gaming performance issues triggered by the KB5066835 Windows 11 October 2025 cumulative update, while Microsoft released out-of-band emergency updates to fix extended security updates (ESU) install errors and a Windows 11 hotpatch install loop.