Windows 11 26100 specific c0000005 crash in Modern Context Menu Shell Extension (ExplorerMenu.Shell.dll)

The supported guidance in the available documentation is limited, but these points are directly relevant to an Explorer context menu shell extension crash on recent Windows 11 builds:

1. Run and test the shell extension in a separate Explorer process. Add this REG_DWORD value:

HKEY_CURRENT_USER
   Software
      Microsoft
         Windows
            CurrentVersion
               Explorer
                  DesktopProcess = 1

Then sign out and sign in again. This causes the desktop and taskbar windows to run in one Explorer.exe process and other Explorer and folder windows in a different Explorer.exe process. For shell-extension debugging, this helps avoid stopping and restarting the desktop and taskbar, and it improves isolation if the non-desktop Explorer process terminates.

2. If the issue involves a shell extension DLL not unloading promptly during debugging, shorten the inactive unload period. Add this registry key:

HKEY_LOCAL_MACHINE
   Software
      Microsoft
         Windows
            CurrentVersion
               Explorer
                  AlwaysUnloadDll

This is useful when debugging because the Shell unloads a DLL only after its usage count reaches zero and it has remained unused for a period of time. Changing this behavior can make repeated test cycles easier.

3. A crash pattern tied to right-click or legacy context menu invocation can indicate a context menu handler problem. In a similar Windows 11 24H2 case, failure on Shift+Right-click and Show more options was associated with a third-party context menu handler causing an unhandled exception when the legacy IContextMenu path was invoked. The accepted troubleshooting approach was:
   • Open Event Viewer.
   • Check the Application log.
   • Filter for Event ID 1000 at the crash time.
   • Inspect the Faulting module path.
   If the faulting module is a non-Microsoft DLL, that points to the extension or another integrated shell component involved in the crash path.
4. There is a documented Windows 11 enterprise issue where Explorer, Start, taskbar, and other XAML-dependent components can fail after certain updates because dependent XAML packages do not register in time after update installation. This issue affects Windows 11 versions 24H2 and 25H2 in some enterprise or managed environments, especially around provisioning and non-persistent environments, and can present as:
   • Explorer.exe crash on start
   • black screen after sign-in
   • Start menu not opening
   • taskbar not rendering
   Microsoft states this issue is addressed starting with updates released June 23, 2026 (KB5095093), with broader availability in the following monthly update. If affected devices are on updates released before late July 2026, installing the latest update is the documented resolution.

Based on the available material, the most grounded investigation path is:

1. Reproduce with DesktopProcess=1 so the shell extension can be tested in a separate Explorer process.
2. Capture Application log crashes around the repro time and confirm the exact faulting module path.
3. If repeated test iterations are needed, use AlwaysUnloadDll to make DLL unload behavior more debugger-friendly.
4. Correlate affected devices with whether they were on pre-resolution Windows updates from the June–July 2026 timeframe, especially in managed or enterprise deployments.
5. Validate behavior again after the latest cumulative update, because Microsoft documents a June 2026 fix for a class of Explorer/XAML startup and shell failures.

Warning: registry changes affect Explorer behavior system-wide for the signed-in user or device. Use them only in a controlled test environment and revert them after debugging if no longer needed.

• Debugging with the Shell
• Trying to run ADUC "as different user" causes Explorer to crash. - Microsoft Q&A
• KB5072911: Explorer, the Start menu, and other XAML-dependent apps might not start or close unexpectedly on some enterprise devices