[FR] Corrupted Lots/Houses disappear in saves with lots of rental units

Today I had my second experience with neighbouring lots reverting to default lots.

1. The first time it happened was when For Rent came out and I placed my first residential rental - when i went back to manage worlds it suddenly showed as 0 simoleons worth, so i went back in and all disapeared. I didn't save that day and never touched residential rentals anymore, and deleted the one that came with  Tomarang as well, after first removing all assigned rooms and any people owning it. I never had the issue again.
2. Today I placed multiple lots from gallery into multiple worlds, just to try out some lots, and I hadn't saved for hours. I only moved from lot to lot, placed from gallery, placed some other alternatives, and moved to the next. When in Cuidad enamorada, in the neighbourhood where the penthouses are, i placed some alternatives for the gym on the ground lots (only community lots, including lots that were offering me to change lot types) and then moved over to the nightclub venue, and that's when all 3 lots around the nightclub reverted back to default. I was so shocked that I didn't dare to save and restarted and luckily it was working again, but now I'm not sure if it will happen again. I wonder if it is a memory issue, of keeping all my lot changes in memory without saving for quite a while? I'm guessing this, because my usual play style is just placing 1 lot at a time, then switching to live mode, testing the lot and only then saving, and moving to the next lot afterwards. So todays long test session was different than usual. I also am playing in a big rotational save where all lots are placed from galllery, no empty lots in this save, and i just bought Adventure Awaits and was placing everything there freshly as well. I regularly check Willow Creek if lots are reverting, out of fear it may start happening to me, given that my save is a "forever-save" since 2020 and my save files are 170 MB big (even though I regularly clean out households and photos). It looks like this issue can even happen without residential rentals, so wanted to share that insight here.

UPDATE:

After reaching a corrupted state yesterday and quitting without saving, I today was able to reproduce it again, and this time saved just before, and then again during corruption with a "save as" copy. Happy to share my save files with the devs. I reproduced it again also without mods.

Learnings:

1. It seems like replacing some simple builds with heavier builds was enough to reach the max limit that seems to corrupt the save file, as I had the same amount of builds in the save before and after reaching corruption ( = all lots built out in all existing worlds of all packs there are up until and including Adventure Awaits)
2. I did not have any residential rentals in my save, it seems to be just a max amount of objects, which may be amplified with residential rental use, but is not required to achieve it
3. When I placed my last bigger build that pushed me over the limit, I was seeing ALL neighbourhoods with default buildings, except the building i was loading into. I could test this even just in build mode from manage worlds, so the testing doesnt require loading into Willow Creek as I thought before, it will be broken everywhere I load into build mode.
4. Deleting some builds made the neighbourhoods go back to normal again after they had already corrupted, which is one more indication that there is a max limit
5. I wonder if the similar issue, that adjacent apartments are becoming completely empty when loading into an apartment is related, it seems like a similar problem, but I had this before reaching this full corruption state.

=> This sadly leads to the terminal fact that I can't buy any DLC with worlds anymore, as that will push my beloved save over the limit. It also makes me realise that starting from zero again will ultimately end up in the same result, so there seems to be no way out of this issue :( 

I really hope the devs can fix this, as this is the only game I play and the only save file I played since 2020, I'm so sad :(

UPDATE 2: I just realised there is another bug report that is for the same issue without residential rentals - so sorry I didn't realise there were 2 similar ones. I will copy this post into the other one, given the other one mentiones that it can happen without residential rentals.

Did most PC people in this thread already try if the new memory boost helps this issue of reverting lots when residential rentals are involved? I just did, and it un-reverted them, but my issue was without residential rentals. 
Still worth a try!!
I logged my experiences with it here as well, add yours here too, if you find any issues with that mode, I think the dev team wants some feedback about if it is helping our issues: Memory Boost Technical Issues and Feedback Thread | EA Forums - 12559480 

memory boost is a hardware feature for better performance for weak laptops, hardware optimizations doesn't change anything about the software bugs so i don't think that it affected the lots, perhaps it was just a coincidence 

I tried it because I saw someone else having luck with this specific issue and memory boost, and in my case it had the same positive effect. I don't know how it affects it, but as the format of the save file seems to change with this mode, it could be that a certain memory space is now planned out larger than it was before and therefore avoids the issue of reaching a object limit in the save file.

I'd just try it out, it's quick and doesn't hurt to know if it fixes it for you or not.

this actually makes sense, sorry, i didnt know it actually changes the safe file itself 

Yeah they wrote that it makes it incompatible with the previous format, which is why they add a label to the saves saved with the memory boost mode, and keep a safety copy of the version without memory boost mode, that can be run when you switch it off again.

Definitely make a backup before you try it, as they do say it is in beta, so be careful while testing on just a copy of your save so you don't risk losing anything important to you.

 I had hoped the new Memory Boost feature would finally help, and while it does make the game run smoother, it hasn’t addressed this issue at all. In fact, it’s made things worse.

I now have several lots that are completely empty when loaded. They still appear on the map initially, but once visited, they’re just blank lots. And then thereafter, they also show as blank on the map. Previously, I only had neighbouring lots showing as default. Now entire builds are gone. Great.

I’m honestly exhausted dealing with this. It’s been almost a year since this issue was first reported, and it all started with the For Rent expansion... which is now nearly two years old.

At this point I’m worried my save might be ruined. It would be great if we could get some real information instead of the usual "We’re aware of the issue and we care about you" corporate responses. If communication were more transparent, maybe progress would happen faster!

So after poking around a bit with Sims4Studio in my save file... I think I may have found a possible reason behind the save corruption - specifically when lots suddenly become unplayable, missing, or get stuck on an indefinite loading screen.

While looking through my save data, I noticed a consistent pattern:

• Lots that are Rental units have a Zone Object Data file of only 9 bytes.
• These lots appear to store their object positional data inside the parent lot instead. Makes sense.

However, the specific lots that have become corrupted in my save also now show 9-byte Zone Object Data files, even though they were originally regular residential lots. 

Looking at the raw data inside and we see it's identical to the entries for subrentals:

{
  "ZoneObjectData": {
    "zone_id": "0x07220ABB345BB1A3",
    "architecture_data": [],
    "objects": [],
    "sub_venue_keys": null,
    "active_data_index": 0,
    "is_modified_from_lot_template": false,
    "architecture_bundle": {
      "U1": "0x00000000",
      "U2": "0x00000000",
      "Records": [],
      "Version": "0x00000001"
    }
  },
  "DisplayName": "Oasis Springs: Nookstone",
  "TypeName": "ZoneObjectDataResource",
  "Key": "00000006-00000000-07220ABB345BB1A3"
}

Note: A normal empty lot (i.e. one that that has been bulldozed is not this minimal and still contains a lot more data than this).

Lots that are unaffected and play normally have Zone Object Data filesizes of between 50kb and 2MB which makes sense given complex builds.

(I won't paste the contents of the data here as it's huge but needless to say "architecture_data" and "objects" are all populated out with all the positional data)

This suggests that at some point, the game overwrites or misflags these lots as rentals, but without any valid parent/child data relationship.

When that happens, the game can no longer find the expected object or zone data for those lots. Resulting in broken or missing lots, failed loads or resorting to using game defaults.

Interestingly, in my save, three worlds have been decimated by this corruption: Oasis Springs, Del Sol Valley and Magnolia Promenade. All other worlds were unaffected. Unfortunately though, poor old FutureSims Labs was also zeroed out by the issue. No more active career for my science sims in this save it looks like!

So in short:

It looks like the game is mistakenly treating normal residential lots as rentals, wiping their zone object data with a non-existent link to presumably a parent lot which the game cannot find or doesn't contain relevant data.

I have no idea what causes this, but I would imagine it happens at the point of the game writing lot data to the save file. 

If anyone from EA or the modding community can confirm whether the game re-uses the same data structure for rentals and other lot types, it might help narrow this down. Hopefully this information will come in useful to someone.

Unfortunately if my findings are correct, it does look like this kind of save game corruption is irreversible, so the Memory Boost may already be addressing this issue but it was unable to rescue my existing save because the data is already gone.

Again, EA/Maxis. Please talk to us and be honest if this is the case.

Hey Kweeky​ would you be happy to share your negative experience with this issue in combination with Memory Boost, in the Memory boost feedback thread as well, this could be super important for dev team's progress: Memory Boost Technical Issues and Feedback Thread | EA Forums - 12559480