@Loretta88 As you may already know, Error 12 is an out of resources condition, usually but not always related to Sims 3 going over its RAM limit. The 32-bit Mac version you're running unfortunately has a limit of 2 GB rather than the ~3.7 GB of the Windows version, so that's the likely cause of your Error 12s, and it can be quite difficult to manage. I remember from my days playing this version that even a new save could use 1.5 GB memory, so you don't have a lot of room to work with.
One thing you can always do is purge RAM. This isn't a cure-all and usually only frees up a little bit of memory, but that can sometimes be the difference between the save succeeding and not. Here's how to do it:
https://bluebellflora.com/resetting-ram-during-gameplay/
Please keep in mind that both the system's and the game's memory use matter: Sims 3 won't even be able to use its theoretical maximum 2 GB if your computer has less free RAM than that. So shutting down unnecessary apps can also help, especially if you only have 4 GB memory installed.
Aside from that, the typical suggestions are not Mac-specific. The single largest resource hog is memories, so I'd suggest disabling that system entirely unless you really enjoy using it. (In that case, use a mod to control the number, e.g. "No or fewer automatic memories" by velocitygrass.) Disable the interactive loading screens and the in-game shopping experience as well. Don't open Origin at all while you play. When your sims travel, save/quit/reload immediately before and immediately after: travel transitions use more memory than live play, as you might imagine given that an entirely new world needs to load.
Additionally, it can help quite a lot to build in a new save, or even a custom empty builder's world. Building takes extra resources, especially if you spend a lot of time using Create a Style, and going from that back to live play often causes problems. A new save uses less RAM than an existing one, so the game has more room to maneuver. You can always place your completed builds in your existing save when you're ready.
This page has more useful tips. You can ignore the ones that clearly only apply to Windows, but many are universal.
https://www.nraas.net/community/TIPS-FOR-BETTER-GAME-PERFORMANCE
So I tried adding all the mods you recommended (errortrap, debugenabler etc) and when I tried to load the game I got an error message that read “it looks like you have installed an unofficial game modification that does not match your current version of them sims 3. We recommend either uninstalling them or get updated versions of them - otherwise you may experience crashes or serious bugs” and it was at this point, and because of what you’ve explained about error code 12, that I decided it’s finally time to splurge on a new computer 😂 I’m amazed that I’ve been able to play this long a 2011 Mac at all so I think it’s really time for an upgrade.
Thank you so much for all your help though and I hope at least other people can results from this help!
@Loretta88 If you downloaded the wrong version of ErrorTrap, that could explain the error. So could not having a fully-updated game.
Regardless, if you've decided to get a new computer, now is a reasonably good time to buy, at least for Windows PCs. Let me know if you'd like help picking something out. I can take a look at anything you're considering, or, if you prefer, I can list a few suggestions. In the latter case, please list your budget and country as well as any other details that matter to you: laptop or desktop, storage space, etc.
