Sims 3 crashes on startup

@SummerSloane  I'm sorry, I thought you'd said somewhere that you tested in a clean folder.  But reading over your post now, I see neither of us mentioned that, which makes me feel silly.  Yes, of course it could be your mods.  And while your mods could have been corrupted when the files were moved around, it's also possible that the files are intact but you have a bad mod.

Another possibility is that you have a mod that's dependent on other content you don't have installed.  Two common examples are having NRaas Cupcake without the store bakery set (or having a corrupt install of the set), and having the MasterController Progression add-on without both the base MC and StoryProgression modules.  The fix in either case is to remove the mod.

If the above isn't relevant, try downloading a fresh copy of one mod, something confirmed compatible with patch 1.67 and/or 1.69 (either or both, doesn't matter) and adding it to your user folder.  Let me know how it goes.

For the launcher crashes, have you added any other content aside from the mods, and does the launcher crash when there's no extra content present at all?  It could be something small, for example the launcher's installer hangs on me whenever I've blocked the game's ability to write to FeaturedItems.

@puzzlezaddict so i just downloaded my sims3packs without any mods in the folder, and had no crashes. it absolutely is a bad mod then! going to do a 50/50 and try and find the bad mod, but will let you know if i have any other problems. Thank you so much!

@puzzlezaddict So after taking out all my mods, I downloaded my sims3packs successfully. I then tried the 50/50 method, but nothing needed to be taken out! My game is running perfectly now. I don’t have any complaints, but any idea why this happened?

@SummerSloane  That's definitely odd, and my first thought is that you happened to not put back one mod or you downloaded a fresh copy or something else that means the content you're using now isn't exactly the same as the content you were using before.  Maybe you didn't download a corrupted Sims3Pack this time around?  But if you're sure that's not the case, then I'm stumped.  It's not even one of those things that "just happens sometimes," it's really very strange.

What I will say though is that as long as the game is working the way you want, nothing else matters.  I'd suggest making periodic backups of your Sims 3 user folder though, in case you run into any other trouble and it's easier to restore an old copy of the folder than to reorganize/reinstall everything from scratch.  I make a backup whenever I install more store content just because the launcher and store are so finicky, and I really don't want to spend an hour of what could have been playtime reinstalling all my store content.