@EmilyBAlfie sure thing
In your sims game folder is a save folder. It is usually located at:
Documents/Electronic Arts/The Sims 4
Drag the saves folder to your desktop
Now, when you run the game, no saves folder, so a new one is created.
Close the game
Go to your desktop saves folder and open it
You should see something like:
Slot0000asave.tmp
Slot00002.save
Slot00002.save.ver0
Slot00002.save.ver1
Slot00002.save.ver2
Slot00002.save.ver3
Slot00002.save.ver4
Slot00004.save
And so on. Each time you use the save function for a game, it saves in one of the five versions. So!!! Hopefully, somewhere in those multiple saves is one that isn't corrupted and will save properly. However, the temp save files are almost always bugged so ignore them.
So drag a save file like slot0002 ver0 from the desktop save file into the documents/electronic arts/the sims 4/saves folder.
Run the game. Load that save. Do something that allows the game to progress - walk around, have a convo, whatever - the see if it saves without the code 0 error.
If the error occurs, move it back to the desktop folder. Repeat the process with Slot00002 ver 1....then ver 2...then ver 3 ....etc until you find one that works.