macOS Monterey: unable to keep a new desktop wallpaper configuration

Finally I have found the solution to resolve the problem: Delete the Picture Database File

with this method:

If none of the above fixes help you, the problem might be with your wallpaper’s database

file. This file is called desktoppicture.db, and it stores your Mac’s wallpaper

configuration.

If the database file (or .db file) is corrupt, your Mac will have issues loading the

wallpaper after a reboot and will opt for the default wallpaper instead. To fix this, try

deleting the database file linked to your desktop picture.

Don’t worry, this isn’t a complex process, and deleting this won’t damage your device.

Just follow these steps:

1. Open Finder and use the Shift + Cmd + G keyboard shortcut to open a command

dialog box on your desktop screen. You can also click Go > Go to Folder to open this dialog box.

1. Paste the path ~/Library/Application Support/Dock/desktoppicture.db into dialog box and click Go.
2. This should immediately start Finder, which will redirect you to the folder containing
3. your wallpaper’s database file. Right-click (or select and Control-click) on the Desktop Picture database file.
4. Click Move to Trash to delete the file.

6. Pick a static wallpaper and restart your Mac. macOS will create a new database file

for your wallpaper once it reboots.

It worked for me, finally !

Hope it will be useful for some people !

This is the screen after rebooting...