Mac: Save loads normally but Save & Save As always fail (Error 21)
Hi everyone,
I'm hoping someone can help because I've spent the last couple of days troubleshooting this very thoroughly, with the help of ChatGPT, and I've reached the point where I think this needs someone with Sims-specific save expertise. I think this may be an unusual save corruption issue rather than a standard Error 21.
I'm on macOS.
The problem
My main save (around 29 MB) loads perfectly and appears completely normal.
I can:
- Play normally for as long as I want
- Switch between multiple households
- Travel between worlds
- Enter Build/Buy
- Enter CAS
- Interact with Sims normally
- Everything appears to function correctly
The only thing that doesn't work is saving.
Both Save and Save As immediately produce:
Error Code 21
The game failed to save. Error Code: 21
The save has several years of gameplay (it's my primary save and contains almost all of my Sims history), so I'm trying everything possible before giving up on it.
How this started
My game had been working normally until a series of events happened around the same time.
I had recently moved my Mac's data into iCloud as part of setting up my computer again.
I then attempted to place a household from the Gallery. After placing it, I discovered that it required the Lovestruckexpansion pack, which I do not own.
Shortly afterwards I began experiencing Error 801, along with obvious world corruption, including:
- missing lots
- floating apartment objects
- missing buildings
- broken world terrain
At that point the save was clearly unusable.
To recover, I restored my Sims 4 folder from a backup that I had stored on an external hard drive and copied my recovered saves into that installation.
After doing that, the world corruption disappeared.
The game now loads normally and appears completely healthy.
However, ever since recovering the save, it has consistently produced Error 21 every time I attempt to save.
What I've tested
I've spent quite a bit of time trying to isolate the cause.
I've confirmed the following:
- No mods or custom content installed.
- Brand new games save normally.
- The game itself appears to be functioning correctly.
- The problem only affects this save.
- Multiple households inside this save all fail to save.
- Build/Buy works.
- Create-a-Sim works.
- Travelling between worlds works.
- I restored older backup versions of the save (ver0/ver1/ver2), but they all produce the same Error 21.
The biggest clue I've found
The most interesting thing I've noticed is what happens when I choose Save As.
The game immediately throws Error 21.
It never creates a new save slot.
- No new Slot_0000000X.save file appears in the Saves folder.
- The timestamp on my existing save also never changes.
- There are no new LastException files created when the error occurs.
Because nothing is ever written to disk, it almost seems as though the game is failing before it even begins the save process, rather than failing while writing the save.
Things that do NOT appear to be the cause:
As part of troubleshooting, I've ruled out quite a few common causes:
- Mods/CC
- Game installation
- General save permissions (new saves work normally)
- A single household (multiple households fail)
- The save simply being unreadable (it loads and plays perfectly)
My question is has anyone seen Error 21 where:
- the save loads perfectly,
- the world appears completely normal,
- gameplay works indefinitely,
- but both Save and Save As fail immediately, and Save As never even creates a new save file?
I'm particularly interested in whether anyone has seen this after recovering from Error 801 or after placing a Gallery household that required a pack that wasn't installed.
I'm also happy to upload a copy of the save if anyone is willing to inspect it.
Thank you!
FYI, I have backups of the save, so I'm comfortable sharing a copy of it privately if that helps diagnose the problem.
