@sparilis Most crash logs won't tell you much, if anything, about what is causing the crash. There are some exceptions, but the logs are generally junk.
What I suspect is that you're running up against the RAM limit for the game. Unlike its Windows counterpart, TS3 for mac can only use 2 GB RAM at a time, a byproduct of the method that was used to make the game compatible with mac OS. (Google TS3 cider if you're curious.) Frankly, I'm surprised you can play at all with that many EPs installed, much less with a multi-generation family. In particular, Pets and Seasons are by far the most demanding EPs, followed by IP and ITF, and most people find that running them on a mac is nearly impossible for any length of time. On top of that, the longer a game goes on, the more RAM it requires to load and maintain. So while your town may be corrupt in some way, it's just as likely that it has simply accumulated too much data to stay under the RAM limit.
Travel transitions require extra RAM, as you've seen, as do Edit Town and CAS sessions. (Hence the other crashes.) Removing the .nhd file of a travel destination only resets that world, as if your sims had never been there or met anyone. (Don't do this if you ever want to go back to the world or invite foreign sims you've already met for a visit.) We're not supposed to talk much about mods here, but you seem to have that under control already. (Just make sure they're all up to date.) A reset of the entire town could help, but perhaps only a bit.
So, what can you do? The RAM limit is always going to be a problem, but there are a few steps that can mitigate its effects. First, make sure your computer is completely offline while you're playing. Even if you don't sign in, the game will still deposit files in your FeaturedItems folder, which takes resources. Also, you can clean that folder out; the stuff inside is useless. If you must be online, at least turn off the in-game shopping experience. Lower graphics settings use less RAM as well. Once you've loaded a town, purge RAM by terminal command, and keep doing so throughout gameplay (see link below). Monitor your RAM usage in the Activity Monitor, and when you see it closing in on 2 GB, save, quit (without saving), and relaunch.
https://bluebellflora.com/resetting-ram-during-gameplay/
You can bypass the launcher when you start up as well, since it takes extra resources to load (even more if you're online):
https://bluebellflora.com/sims-3-how-to-bypass-the-launcher-on-a-mac/
Keep your families small and their personal inventories close to empty. Also try to avoid overloading your lots with thousands of items; the game needs more resources to keep track of everything. Keep your saved patterns and styles to a minimum, and move screenshots or videos out of your TS3 folder before you play again. In fact, keep your game folder (in Documents) as empty as possible. Turn memories off entirely, and delete all existing memories, other than maybe a few per sim (memories are a huge resource hog). If you use cheats like buydebug, turn them off whenever you're done with them. Clear the five cache files after every play session. Always save separately, then quit without saving. The processes together take up more resources, and if the save fails, the game will quit without warning you.
Whenever you want to do something that takes extra RAM, like travelling, make sure to do so as soon as you load a save. Even if you're purging RAM frequently, usage will build up during gameplay as your computer loads more and more data. If you're planning to use CAS or Edit Town, the same rules apply. Build only in a new game, then save your work to the library so that all you have to do in your existing game is place the lot. During a travel transition, you can also turn your graphics down to the lowest settings until your sims arrive safely. When they do, it's probably best to quit and relaunch before proceeding with the vacation.
I'm probably forgetting some stuff, but that still seems like a lot. This is the part where I should mention that I recently threw up my hands and just Bootcamped my macbook. It's been great. I don't know if it's feasible or something you'd want to do, but with all those EPs in play, it might be your best option. Additionally, if speculation is true, the next mac OS will not support 32-bit apps at all, which will mean no more TS3 for mac past High Sierra. Just something to keep in mind.
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I don't work for EA. I'm just trying to help fellow players with their games.
