Exception Raised Sims 3 will not launch

@wastedlizzy  The most common cause of that particular error is the game running out of memory.  No matter how much RAM you have installed on your computer, Sims 3 can only use 2 GB in macOS, and if it goes over, it will crash.  The updated version of Sims 3 that's coming out will hopefully have effectively no memory limit, but until that's released, the only thing you can do is try to manage RAM use as much as possible.

If your computer happens to have 4 GB memory or less installed, you can hit the limit even more quickly, since macOS can take more than half of that for itself.  If you have less than 8 GB memory, it's a good idea to not run anything else in the background while you play, or at most one or two Safari browser windows.  (Other browsers use more memory, sometimes even with only a couple of windows open.)

One thing that may help is purging RAM while playing, although that tends to only have a small effect:

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

In general, there are many steps you can take to keep resource use down in your existing saves.  None of these are fixes, more like small improvements you can make that may collectively help a significant amount.

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