How to Fix Missing Entry: Pca Wallpaper App Detect on Windows 11 24H2?

When users update their Windows 11 to the latest 24H2 version, they randomly encounter the error ‘Missing entry: PcaWallpaperAppDetect’. This is a scheduled task in Windows and is related to the Windows wallpaper service. This error occurs due to compatibility issues and sometimes due to the use of third-party wallpaper services like Wallpaper Engine.

1. Run SFC and DISM

The problem could be due to corrupted system files. Running the SFC (System File Checker) and DISM (Deployment Image Servicing and Management) utilities is recommended to address this. These tools scan for corrupted files, perform repairs, and restore system integrity.

1. Open the Search menu, type cmd, and run the Command Prompt as an Administrator.
   
2. Enter the following commands:

   sfc /scannow
   Dism /Online /Cleanup-Image /RestoreHealth

   

3. Restart your PC once the processes are completed.

2. Use Program Compatibility Assistant

The Program Compatibility Assistant is a built-in Windows service that helps in running older programs on newer devices. Running it will scan the issue and fix it, which might help in solving the problem.

1. Open the Search menu, type ‘Run programs made for previous versions of Windows’, and open it.
   
2. Follow the on-screen instructions.

3. Perform a Clean Boot

Third-party services can interfere with system files and cause issues. To determine whether they are causing the issue, try performing a clean boot of Windows. A clean boot stops all non-Microsoft services from running at startup, which might resolve the problem.

1. Press Windows + R, type msconfig, and press Enter.
   
2. Navigate to the Services tab, tick the Hide all Microsoft Services checkbox, click Disable all, and click OK.
   
3. Press Windows + SHIFT + ESC to open the Task Manager.
4. Switch to the Startup tab and disable all third-party programs.
   

4. Delete Third-Party Wallpaper Services

If you have any third-party wallpaper services installed like Wallpaper Engine, Lively, etc., they can interfere with the system and stop it from working. To fix this issue, you can uninstall all the third-party wallpaper services.

1. Press Windows + I to open Settings.
2. Go to Apps.
   
3. Look for any wallpaper services installed and uninstall them.

5. Use Task Scheduler

Task Scheduler is a Windows utility that is used to stop Windows routine tasks. You can delete the PcaWallpaperAppDetect task using Task Scheduler, and Windows will not allow it to launch during startup.

1. Search for Task Scheduler in the Search box and run it as Administrator.
   
2. Go to Task Scheduler Library > Microsoft > Windows > Application Experience.
3. Find the PcaWallpaperAppDetect task from the list.
   
4. Right-click it to choose Delete.

6. Uninstall Update

If none of the solutions work, you can uninstall the update. This issue is caused by the recent 24H2 update, and uninstalling it will roll back Windows to the previous version and solve your issue.

You can check our article on how to Uninstall Windows Update.