Issue

Windows 10 at random times shows following error message: 

Save a Theme
Windows can’t find one of the files in this theme. Do you still want to save the theme?

Resolution

The error comes from Host Process for Settings Synchronisation which is responsible for syncing Windows 10 settings between computers via Microsoft Account.

If you don’t need your Theme to be synced between computers the fix is pretty straight forward:

• Go to Settings > Accounts > Sync your settings and disable Theme under Individual sync settings
  

If you want Windows theme to be synced, you can try following:

• Sometimes simply toggling the above option off and back on fixes the issue.
• Select a different Theme (Settings > Personalization > Themes), or download a new one.
• Delete and re-install your theme.

August 2018
Windows 10 Pro (1803)