I think my save is corrupted

@kikilopez18  Regardless of which of the approaches below you decide to use, the first thing to do is delete the five cache files in Documents > Electronic Arts > The Sims 3.  While you're troubleshooting, please delete them every time you quit the game.  For reference, they are:

• CASPartCache.package
• compositorCache.package
• scriptCache.package
• simCompositorCache.package
• socialCache.package

If you use mods or are willing to try a few, please install NRaas ErrorTrap, Overwatch, Register, and MasterController.  You can find descriptions and download links here:

https://answers.ea.com/t5/Technical-Issues-PC/Sims-3-Common-Game-Fixing-Mods-Hero-Approved/m-p/9838855#M244208

The first three do their work automatically, without need for user input; MC doesn't do anything unless you use it to issue a command.  Please load your save, let the game clock run for a few sim-minutes, click on City Hall, and select NRaas > MC > Town Options > Reset Everything.  This might take a few minutes, depending on the speed of your Mac.  When it's done, let the game clock run for a few sim-minutes more, then quit and reload the save, and see how it runs.

If you're not interested in mods, there's not nearly as much you can do.  One thing that might help is bringing up the cheats console (cmd-shift-C in the 64-bit Mac version) and entering resetsim * (with the asterisk).  This will reset all sims in town, so it'll help if the problem is a stuck sim, but that's not the only cause of crashes like this.

If you use custom content and the above doesn't help, try removing all the cc.  You don't need to save your progress; the point is to play long enough to see whether the game crashes again.

Hi puzzleaddict! Thank you for responding . I’m going to try out the mods you recommend, I’ve never ever used mods In the sims 3, just CC so a little scared. But ill try. If they fix the issue, do I have to keep the mods? 

and if it helps, I noticed I crashed a bit after I noticed a zombie sim make it past the celebrity fence in our house, no holes or anything and it’s in the middle of the night. I tried replacing their home and the zombie guy is gone but no luck. 

I’ll try the reset sim and cc as well, I’m not so sure it’s CC because out of my 4 or so saves it’s the only one with this issue but I’ll still try. There isn’t any other known way to fix these sorts of things? I t think my last save corrupted , there isn’t something we can do in the saves file on my computer with the backups or anything? 

@kikilopez18  Zombies can spawn inside a fence if the lot has a spawn point, which it probably does.  They can even spawn inside a locked garden if there's room.  A zombie can get caught unable to leave on a lot if there's no way out, but using the resetsim cheat on them should make them go away.

Most bad custom content is only a problem if a sim is wearing it, or if the wrong sim is wearing it, for example if it's not properly restricted to certain age groups.  So a cc item might sit in your user folder causing no problems at all until it gets assigned to a sim, then that sim has a reason to wear that outfit.

For the mods, yes, they're removable, but I'd suggest keeping them in play for the long-term health of your saves.  The game itself doesn't have a mechanism for garbage collection, so without these mods, old data will hang around indefinitely and probably cause corruption sooner or later.  I'd never play without NRaas mods, and many Sims 3 players feel the same way.  Like I said, you can just ignore the mods and let them do their work in the background, so other than clicking through the occasional notification, you really don't need to do anything at all.

For your already-corrupted save, you can try loading a backup, either one you've made or the automatic backup the game creates.  You'll find the latter in Documents > Electronic Arts > The Sims 3 > Saves.  It'll be a folder with the save name plus a .backup extension.  Rename the save and delete the .backup, so the name ends in .Sims3, and the save will be available to load at the Main Menu.

Loading a somewhat corrupt save with the NRaas mods in place, then running a MasterController town reset, may or may not be enough to recover the save.  For a save that's already shown signs of corruption, I would definitely not play the save without mods at any point, just in case some other problem is lurking and ready to wreak havoc.