The item is corrupted, or cannot be detected by the system.
If you are getting this error when selecting a theme, try to re-download it. Go to Notifications > Downloads, highlight the content, and press the OPTIONS button to delete the theme. Then go to Settings > Theme to re-download the content.
For other content, go to the Library and check that you have the license to the content. If you have the content and are still getting this error, try the below steps:
Re-download the content
Go to Settings > PSN > Restore Licenses
Shut down the system and reboot in Safe Mode. Select 5. Rebuild Database.