Hello @Samsung_JKyp539 ,
If your galaxy themes setting is causing an error message, it could be a bug in the theme itself. I would recommend you reset your settings to refresh your phone and then download a different theme and also make sure your device is updated.
Disclosure - lt will reset customizations such as Wifi and Bluetooth pairings.
The step by step instructions are:
Settings > General Management > Reset > Reset Settings
Hope that works for you. If you have any other concerns just reply here.
Be sure to click " ✓ Accept as Solution" when you find an answer that works for you