Game crashes in 1 save file and not another

@tlobliviate  Wow, yes, you're managing to run all those packs together in macOS.  It's not surprising your save would crash constantly then, given how much memory it uses.  The Windows version can use up to ~3.7 GB RAM at a time (4 GB minus some overhead), but the Mac version is hard-capped at 2 GB due to the way it was initially programmed.  The Windows version also originally had a 2 GB memory limit, but it was patched to be able to use more; the Mac version never was.

As you've seen, and I've seen from time to time as well, that doesn't mean the game will immediately crash if it goes over the limit.  I haven't paid close attention in a while, but it's possible macOS does a decent job of compressing unused data.  It's also possible that the Activity Monitor isn't reporting the data correctly.

It's kind of a moot point though.  This particular save is using too much memory right away, and so the crashes are totally unsurprising.  Opening houses isn't going to help either: it takes more RAM to simulate two houses and the sims inside than one.  Sims 3 is also notorious for not releasing all the memory it was using but no longer needs, so closing a house again might not free up all the RAM that was used when it was open.  Checking random data like ages and relationships should only have a minimal effect, if any.

At this point, you can keep playing the save and hope for the best, but there's no guarantee things won't get worse.  There are ways to try to keep memory use down overall, from disabling the interactive loading screens and the in-game shopping experience to purging RAM every so often.  Sim memories are a huge resource hog, although as mentioned before, disabling them now won't remove the data from the existing ones.  Here's a more complete list of things you can do to keep resource use down:

https://www.nraas.net/community/TIPS-FOR-BETTER-GAME-PERFORMANCE

Here's how to purge RAM on a Mac:

https://bluebellflora.com/resetting-ram-during-gameplay/

StoryProgression is also a heavy mod in that running it will take more resources.  I don't know what your settings are, but it might help to slow down the speed of SP, or even play without it in this save if you can stand it.

Given how long you've played this save though, you might end up needing to move your sims to a new world.  If you do, don't use the EA method of calling on the phone and moving; save the sime to the library, quit to desktop, reload and start a new save, then place the sims there.  If you want to keep their house, save it separately.  The sims won't know anyone in the new save, but they'll keep their skills and relationships to each other, as well as their jobs if those jobs exist in the new world.

If there are more sims than just your active household that you'd like to keep, you can save them separately and repair their relationships using MasterController once they're in the new save.  Or you could pack them together with NRaas Porter, which would preserve all the relationships among the sims.  If you end up going that route though, it's best to ask on the NRaas forum.  I've never done this myself, and I know there are small details here and there that can matter very much, for example making sure to pack the graves of ancestors to preserve the family trees.

By the way, I don't think I answered this before, but you asked how to keep sims from moving into town.  There are various StoryProgression options you can use, depending on what you're trying to accomplish—one thing you can do is block a certain empty house from being occupied.  But the simplest approach of all is to remove the fridge from the lot.  Sims won't move into a house that doesn't have a fridge.

Hi again. Thanks so much for all the information! I've been searching the internet for answers to my problems, and really I should have just come here -- you have a solution for everything. 

My game is running much better than it usually does. I was able to play for over an hour without crashes. Of course, the game did eventually crash though. I save probably every 5 minutes, and it never takes more than 3 minutes to save, which is amazing! I've stopped opening and closing houses, as you suggested. Also, I notice that my game is not taking up more than 1.8 GB of memory. I'm not sure why it said 2.3 GB before.

I'm wondering if switching back and forth from sims to an internet browser could be the cause of crashes. I often play in windowed mode and watch youtube at the same time. Could clicking on and off of the game lead to lagging and crashes?

I'm very interested in what you said about saving the sims to the library and making a new world with the same sims. I had that idea before, but when I tried it with one family, I noticed that their family tree did not carry over, and the family tree is a very important part of my game to me. You say if I bring the tombstones it would keep their family tree in tact? Can you explain that more?

And thanks for that fridge tip!!! What a good idea! 

<3

@tlobliviate  Switching between a browser window and the game shouldn't cause crashing on its own, although it can if your system is already running close to capacity with just Sims 3.  Yours has more than enough memory; I'm thinking in this case of the processor, or perhaps that the graphics card is involved in something else you're doing and doesn't switch back and forth well.  Sims 3 also doesn't always respond well to being minimized, at least on some systems.  I find it does fine though if I put it in windowed mode and leave it up.

Playing the game and playing a video at the same time is more demanding than playing one and having the other on pause.  Whether your system can handle those extra demands depends on the specs of your computer, your OS, and other factors.  It's difficult to be sure what's happening on your computer without being in front of it and watching the output of some hardware monitoring app.

It's really speculation though, unless you notice something specific.  At any rate, if the game crashes when you run YouTube or some application at the same time but not when you just play, then that's enough of a pattern to say you probably should avoid doing that.

When you save a household to the library, the sims lose all relationships with people not in that household, and that includes dead relatives.  This is also true of the option to move sims to a different neighborhood through the phone interaction.  The point of using NRaas Porter is that instead of transferring single households, you pack a number of them together, preserving all the info among them.  If you put the tombstones of the dead relatives in the inventory of one of the packed sims, the ancestors' data, and the relationships that follow, will be intact.  So for example, using Porter, if first cousins living in different households bring their dead parents' urns with them, they'll still be first cousins in the new save, regardless of whether you unpack them to the same household or different ones.

The fridge tip is a great idea, and it's not mine.  Someone else posts the suggestion often, and I and others steal it mercilessly.  The nice thing about it is it works whether you have StoryProgression or not, and without having to go through any other mod options.

I see. To be honest, moving all my sims to a new neighborhood, and trying to keep their relationships sounds too complicated. For now, with the errortrap mod, I think I'm just gonna deal with the game as it is. I guess I shouldn't play it in windowed mode. I play in full screen, then save in windowed mode since I'm so used to the game saving for infinity and freezing my computer. 

Now I have to go delete some refrigerators, lol. 

Thanks for all your tips! My game is running so much better than it was.