Save Game Corruption - Testing and Findings From 10 Years of Experience

This is really interesting!  And something I've thought about a lot too, does replacing lots with gallery/own lots cause corruption? Does the game mess up when you introduce too many new lots/sims into it? 

Also that this started even BEFORE  for Rent came out, but FR just made it that much worse by adding new type of lots and complexity of existing ones. 

This is terrifying, & explains why I've lost 3 'forever' saves in the last few years.
So basically, don't play the game how it's meant to be played -ha. 🙃

Hi there ceunon20​ 

Would you be willing to share this backup save file so we can investigate into this further please? If so, please send me a private message with a link to the file. Instructions can be found here: [INFORMATION] How to Send User Files to The Sims 4 Team 

Please also provide any specific steps you've found to reproduce the issue. Thank you! 

Hi Solarie! 

So I did provide my save game on the [PLEASE READ] Save Game Corruption | EA Forums - 5037272 about 5/6 months ago but I had an issue with my Google Drive and unfortunately I lost it.
That's why I'm creating an new and fresh save file to recreate the corruption. 

Right now I'm about to finish Innisgreen and Nordhaven, no corruption was found until now.

Hi DarkSimzzz​ ! 

Replacing lots with ones from the Gallery—or even your own creations—doesn’t corrupt the save file, even if the uploaded lot originally came from a corrupted save.
Lots from the Gallery might carry glitches or bugs, but never a “virus” that spreads through the save.

Still, there’s an interesting relationship between lots and corruption that I forgot to mention…
- Let’s say you decide to build a new house for the Goth family in Ophelia Villa, making a beautiful 30x20 Victorian home.
- A week later, you replace it with an Haunted House you found on the Gallery.
- Two weeks after that, you move the Goths to Ravenwood and turn Ophelia Villa into a cemetery.

Here’s the catch: all this information—from one version of the lot to the next—is stored in the save file and never really disappears. The new lot (the cemetery) is there, but the previous versions still exist in the background, just hidden.
That’s why in many cases of save corruption, lots tend to revert back to a previous version—or even to the original base game version—while the infamous orange “!” marks show up on the map. The problem is that we still don’t know what exactly triggers this kind of corruption.

Now about the Sims...
I’ve never found any direct connection between Sims and save corruption. However, Sims with heavy customization can make your save file larger and more fragile. My advice: avoid Sims overloaded with tattoos, fairies with custom wings, or werewolves with custom fur. Stick to the ones from the base game as much as possible to reduce the strain on your saves.

ceunon20​ Gotchya, thanks for the update! If you do run into an issue again on your current save, please feel free to send that over so we can take a look :) 

I apologize for my rambliness here.

Something I'm reminded of is Pokemon Red (I promise this is relevant). A Pokemon that shows up frequently when the game is corrupted is Rhydon, because Rhydon was the first Pokemon ever coded into the game. Also common is the ever-famous Missingno, because that's the default the game throws up when it knows it doesn't know what Pokemon to display, and third most-common is Kangaskhan, for reasons I don't really know but probably relate to it having a pre-evolution (almost certainly that little baby it carries around) that was cut last-minute due to the Game Boy's memory limitations. Similarly, one of the glitches is called the ZZAZZ glitch because it replaces most of the characters in the player character's name with a ridiculously long string of "ZZ" (the last letter in the alphabet) and "A" (the first letter in the alphabet) characters. Unless the name is the right length to ensure the end byte isn't among the replaced characters, this will render the save unusable because one of the ways the game checks for corruption is to see if the player character's name is within the character limit.

The relevance: Most "file corruption" cases where the save file stops loading come down to that. It's not that the save file is totally unreadable/unusable, but rather that the file has failed the checks that the software (or in some cases, the OS) has implemented to minimize the risk that it runs a program that causes permanent damage to or even outright bricks the software or hardware. It's annoying, but it's a very, very good thing overall. Many netizens (me included) aren't old enough to remember when tech companies either couldn't or wouldn't protect software and computers like that. So there's a tendency to take for granted that software can't hurt anything outside itself and that error message only mean that something isn't working (when they also mean that error prevention and containment are doing their jobs correctly).  You may think you want your potato computer to risk running a large file, but actually, you don't (...unless you like the idea of converting it to a paperweight, I guess).

I'd love it if somebody had diagnostic tools so they can see which precise checks are failing and evaluate if anything from corrupted save files can be rescued. But in the meantime, this is why it's important to clear out the caches on a regular basis or at least after updates/mod installations (data stored in them is supposed to be temporary and is thus vulnerable to becoming obsolete, either because of changes over time or updates, and this can both gunk up the corruption checks with false positives and cause it to become corrupted in a way that's contagious to more permanent files), keep lots and families you're fond of in the gallery or library for retrieval in the event of file corruption, and get to know your computer's limits so you can keep your builds and families safely within them.

Also relevance: If I had to guess as to why Willow Creek is the first to fall, it'd be for the same reason Pokemon Red likes to fall back on Rhydon or Missingno. Willow Creek was likely the first world ever coded into the game. All of the default resolutions to stuff like null pointers are going to point to it because, as the first world ever implemented and one of three included in the base game, it will have the lowest values possible for IDs and things like that. It's also common for software to just move onto the identifier immediately above or below if one it's currently on doesn't work, so that's why the order would always be the same.  If I had to guess, this also applies to lot types, and thanks to the game never really forgetting what a lot has been in the past, lots that start off as residential fall together whereas lots that started off as community lots go one by one. Magnolia Promenade is unusually large and I think not technically attached to any of the other neighborhoods (like it loads a separate area and stuff-- correct me if I'm wrong please, I don't normally play in Willow Creek!), so perhaps it has more anti-corruption countermeasures in place or is smarter about how it uses memory.

Alternatively, Sims 4 started life as an online game. Pure speculation, but perhaps the residential neighborhoods were originally meant to be far less complex, as "home base" lots that wouldn't be very large or expected to hold many Sims and might not even require the internet, whereas the community lots were for various types of private congregations and events, and Magnolia Promenade was a large public lounge. In that case, the residential neighborhoods would have been pushed to the limits of and maybe beyond what they were meant to do when the game was hastily transformed into what we know it as today. The community lots would have been under extra strain too but not as severely as the residential ones since they were meant for gatherings. And if anything, Magnolia Promenade would be under far less strain from not having to handle dozens of Sims moving around the place at any given time while thousands attempt to enter it. And the game never forgets what a lot used to be because, if the online game would be anything like the Sims Mobile, the lots wouldn't be expected to change much period, and something like type probably wouldn't change at all. And a microtransaction-heavy game would benefit greatly from being able to revert purchases easily because it would let EA avoid lawsuits/controversy if somebody's kid ran up a credit card with the game (this happens more often than you'd think with mobile games) and EA could also easily undo fraudulent purchases or accidental freebies this way.

Another thing about corrupted data is that it tends to produce ridiculously high values too. Like with Pokemon Red, the ZZAZZ glitch produces a lot of Zs. Also, if you use corruption glitches to trigger an encounter at the PokeMart, you'll get the "A hooked [Pokemon]" message because, when determining how you got the encounter, the highest possible index value corresponds to fishing. So game only looks to see if the determination value is greater than whatever index value fishing is set to, and with corruption the determination value is guaranteed to correspond to something ridiculously large.  So I would actually wonder if the world associated with the most recent pack (either that you own or in general) tends to be affected more often too-- but this is harder to keep track of because while everybody who plays the Sims 4 has Willow Creek as the first world, which world you have as the last world will vary depending on what packs you own. The last world will also change as you purchase different packs, as new packs come out, and if/when you use the disable pack feature. Plus, more recent worlds have the benefit of actually being designed for the kind of game the Sims 4 is, as opposed to being cobbled together from a very different cancelled game.

Plus I'd be remiss if I didn't mention how this game's code is beyond mere spaghetti. It is basically alphabet soup for Cthulhu at this point. That'll invariably cause it to corrupt itself for reasons beyond mankind's capacity to perceive.

I hope you guys don't mind me ranting here, let me know if I'm off-base in any way. I just find this stuff fascinating.

Interesting findings. I have also done extensive investigation with my game when I experienced save corruption which started for me right after I installed the For Rent EP and I found out that it was directly related to the # and size of lots that I added to my game. For me, nothing related to downloading from the gallery. I "save as" the game often so I was able to go back to a save file where the Willow Creek Archive lot had not disappeared and recover my save file by deleting unused default lots that I did not need to reduce the "bloat and amount of high polygon objects" in my larger builds and then continue to play the game normally until I installed the Lovestruck and Life & Death EP's last December. When I installed these EP's, I did not notice what was happening at first, but I noticed that when I loaded into one of my lots in Willow Creek, the Sims that were in the house I expected to see when I loaded in were all outside on their phones on an empty lot and the house next door to them that was supposed to another one of my houses I added to the game was actually a default house that came with the base game. I was terrified and could not immediately diagnose the problem because I received no error codes, no orange triangles above lots that had disappeared, and other than many of the houses I had added in Willow Creek, the game performed normally. I also forgot to mention that before this happen, I did a test where the Willow Creek Archive lot was corrupted in build mode but when I had a few of my Sims travel there in live mode, the lot was there intact and functional! I forgot what steps I took to correct the problem with the my Sims house that had disappeared but I was able to redownload it from my library and then I went to each of my Sims houses, about 91 at the time because I have 727 played Sims in my game and getting rid of Sims was never going to be an option for me to avoid save corruption. The problem as I kept checking out all of my Sims homes and whether I could load in or not was that houses next door to my Sims in the world that were supposed to be my houses were actually the default houses but if at exited and relaunched the game, my houses would next door would actually reappear so I thought it was a mod issue causing this until I read articles in Reddit that this was another sign of save corruption so to verify that my save file was corrupted, I checked the Willow Creek Archive lot in Build Mode which is where save corruption always starts in my game and it actually was wiped clean! Then thinking that my save file corrupted because I added Lovestruck and Life & Death, I used James Turner's method to remove the 2 packs from my game and then went back to a good save file I had just before I installed the 2 packs and restarted the game and the Willow Creek Archive lot was present and intact in build mode.

So, later to test my theory that the game had a limit to the number of objects that it could hold before it would start to go into what I call "self preservation mode" to start deleting objects to this limit would not be exceeded which triggered save corruption for my game, I deleted 40 of my Sims houses (all of these houses were houses I had downloaded from the gallery originally built by other players when I did not know how the build houses when I first started playing the game back in 2021) and left the houses that I built from scratch. I then used MC Command Center to combine the Sims that no longer had homes with the Sims that still had houses left so that resulted in most of my homes now having 16 to 24 Sims per house which is how I play the game today with no save corruption. I then copied this save file from my Desktop PC to my Laptop PC and turned Lovestruck and Life & Death back on and just as I was expecting, my game worked fine without save corruption because I had deleted almost half of my builds but kept my 727 Sims. My Desktop and Laptop PC's are very powerful gaming PC's so this may be one reason I can add so much to my game and not experience problems because my save file is currently around 120mb but it has been as high as 123mb. Right after I deleted half of my builds, my save file was around 94mb but as I used MCCC to combine households, my save file increased from 94mb to around 112mb and then just going in and updating all of sims and adding some smaller builds my save file grew to 123mb.

However, recently I tried building a house from scratch on the 64x64 lot in Chestnut Ridge and as soon as I reached a certain point in the build, I started experiencing intermittent "forever loading screens" which I know sometimes is a sign of save corruption in my game but not all of the time so I loaded into the Willow Creek Archive lot in Build Mode to make sure it was still there and intact and not missing any items and I saw the dreaded message that you see that indicates your save file is corrupted: "Items Removed - One or more items may not be installed on your computer or the EA Account that is currently logged in does not own these items. One Build Mode item has been removed". If you ever see this message in one of the Willow Creek Community lots in Build Mode, your save file is corrupted and if you keep playing the game, you will reach a point where you can no longer delete lots because of this and then you may trigger 801 codes or not be able to load into lots. So, when I saw this, I just uploaded my partial build to the gallery so I could download it later when I had more "space" in my game and deleted it in game and went back to the save file just before I added the lot and all was good!

A few weeks ago, I had save corruption pop up again when I was adding books to bookshelves in my Sims homes so I just went back to a save file before I started doing this. 

I also used Artificial Intelligence to help me remove the "metadata" from lots that I deleted but still contained the metadata and this is how I reduced my save file size from 123mb, which is when I experienced save file corruption by adding the books to the bookshelves, to now down to around 120mb. Basically, I just went to all of my deleted lots, wiped them clean including the terrain paint, and then turned them into "generic" lots which helped reduce my save file size because I did not know that when I bulldozed the lot, there was still metadata that the lot contained that adds to save file size. Reducing my Sims inventories also helped in reducing the # of objects (or polygons) in my save file which triggers save corruption once you reach that unknown limit of "polygons" which is what AI calls it. 

One more thing, after the Lovestruck and Life & Death scenario that resulted in me spending hours upon hours to "save corrupt proof" my game so that it would remain playable, I complete have stopped updating or adding any new content to my game since January and will not add any more content or update the game until the save corruption issue is resolved. If I had not been laid off my job last summer, I would have never had the time that it took for me to troubleshoot, diagnose, and fix my game after save corruption without starting over from scratch which is not an option for me because save corruption could still creep back up even after starting a new game! Also, I emphasize "my game" because what worked for me and my experiences may not be applicable to anyone else because there are too many variables related to save corruption like mods, platform hardware, combination of packs and kits installed, etc. I still think I benefit by having powerful PC's and by having 2, I can always revert back to a game that is still good on another PC if I mess up testing out something in the game on one PC. 

The biggest advice I can recommend to players that I use to avoid save corruption is, 1) "save as" your game as much as possible even if you end up with hundreds a save files because it's easier to delete the ones you don't need as opposed to losing game progress because you have played in a corrupted save file for too long! 2) Always, always load into the Willow Creek Archive lot in Build Mode as soon as you start the game to check that everything is still there. I have found out the hard way that loading into the lot in build mode while you have already started playing the game is worthless because many times, I did this and saw that all was good and then came back and loaded into the lot after restarting the game and the lot was missing items! 3) Always "Load Save File" as opposed to "Resume" when restarting a game 4) Always delete the "localthumbnailcache" (can't remember the exact name) and other cache files before restarting a game. This always makes my game run smoother because I have found out that as this "localthumb~cache" size increases, the slower the game runs. This file can also be very helpful in detecting a corrupted save file because if you are in game and you check the size of this file and it is 0KB, your save file may already be corrupted! 4) If you see any weird behavior in your game, even weird stuff with Sims, I recommend "save as" your game, shut it down immediately and clearing cache files, and restarting the game and immediately check the Willow Creek Archive in build mode to make sure it did not start "corrupting".

I will always and forever have to use the steps above when I play my game as a safeguard to avoid losing saves to corruption, even after the game is fixed.