First, check your game settings
Open The Sims 4 and make sure both Enable Custom Content and Mods and Script Mods Allowed are turned on. After changing those settings, fully close and restart the game.
Check the file type
Script mods usually include a .ts4script file. Some also include matching .package files. Keep the files together unless the creator gives different instructions.
Do not bury script mods too deep
A common mistake is putting script mods inside too many folders. Keep script mods close to the main Mods folder. A simple setup like this is safer:
- Mods / MC Command Center / files here
- Mods / UI Cheats / files here
- Mods / Gameplay Mods / files here
Cozy rule: If a script mod has not been updated after a big patch, remove it temporarily and check the creator page before putting it back.
Test only one script mod at a time
If your game will not load, remove all script mods, delete localthumbcache, then add one script mod back at a time. This makes it easier to find the one causing the issue.