Happened to me a couple of days ago after returning from a vacation on the rental lot in Cuidad Enamorada. Came home, redecorated their small house a little bit, saved. Changed the swatch on a sculpture, went back into live mode, attempted to save again, got the error code 0.
Deleted the last five or six saves (before the trip to CE, basically went back a week IRL). Could save correctly for a few hours, but then got the error again. It appears to have happened after I edited a game-spawned townie vampire in CAS and added her to a different household I am also playing. (Not the household that originally got the error.) The last successful Autosave file is dated 8 minutes after the first time I saved with the townie in the household.
I can't send you my files (PS5), but I hope this info helps in some way. I have all DLC except a few kits. I can save using "Save As." The save is fairly new, created same day as the Lovestruck patch. I did have this error once before (same save, about a week after patch), but it went away after a few days of using "Save As" either on its own or because I quit the science career and deleted all the crystals and metals from my sim's inventory.