[MOD/CC RELATED] My sim can walk on water

@LeslieKremin

Go to the Documents/Electronic Arts/The Sims4 folder.
Open this folder, look for localthumbcache.package file and delete it. Then look for Options file and delete it also The game will recreate it but without saved errors.
Than open Origin/ Library - right-click on TS4 option "repair game"
Check if your sim still does miracles and walks on the water

I don't work for EA

@AlvaHe

It looks like you have to do it in a more complicated way. Probably not only this one file was affected by CC or mod.
1. Rename The Sims4 folder to "The Sims4 old"
Step 2. Fix the game in Origin
Origin/Library - right-click on TS4 - option "Repair game"
You have to wait until Origin will fix all packs, not only the base game.
Step 3. Turn on the game - a new game folder will be created and you will have two - one old, one new
Step 4. Check if you still have this problem in the newly created game folder. Start a new game with some mermaid and let her swim.
If the problem disappeared and your mermaid can swim:
Step 5. Delete in the new game folder following folders:
"saves" and Tray.
Step 6. Go to "The Sims 4 old" folder and copy - your "saves " folder.
Step. 7, Paste this folder in a newly created game folder.
Step 8. Do the same with Tray folder - it is your library -  and TrayDeleteItems file
9. You can check now if your mods or CC are up to date.
Copy and paste your mods and CC from old mods folder to the new one. First copy the scripts mods every time checking if these mods don't. cause problems. Do the same with CC  If you have a lot of CC try 50/50 method ( divide your CC into smaller batches for example 50 pieces in one subfolder and check these subfolders one by one.)

Step. 10. If all is OK - delete The Sims4 old folder. Now you will have only one game folder working properly.

I don't work for EA