This is the biggest Mac/Sims 3 issue at the moment, apart from the unsupported graphics cards issue which EA STILL haven’t fixed after nearly 4 years…
The Unknown Error is a magical mix of Late Night/Ambitions/Fast Lane/Outdoor Living trying to be installed onto a Mac running macOS 10.11 El Capitan, 10.12 Sierra or 10.13 High Sierra. It’s that simple. We have a thread running over at AHQ where people are posting about it and yesterday a rather super person called coreylamalva414 posted a solution which appears to actually work (go and show him some love if it works for you 💚). His instructions can be found here. You will also need to check that these packs are showing in your Applications > The Sims 3 folder, if not then follow this guide on moving the relevant files.
Edit – coreylamalva414 has uploaded a very helpful video to walk you through the fix:
Edit: I have to just make one thing clear here, this Unknown Error issue is very specific to El Capitan/Sierra/High Sierra/Late Night/Ambitions/Fast Lane/Outdoor Living, there are plenty of other reasons why you may be getting the Unknown Error issue. If you do not have one of these operating systems or packs installed then please do not ask me for help on this page as it is irrelevant. There have always been issues running the game on a Mac and if you have a post-2013 Mac with unsupported Intel/AMD graphics then the game is not technically compatible so getting the game to actually run smoothly would be a miracle.
Threads are starting to pop up on the forums with people moaning that their Sims games will not work properly, or at all, since they have updated to macOS Sierra beta. What a surprise! The operating system is in beta which means it will be buggy as hell and apps may not work properly. If you’ve signed up for the public beta it means that you agreed that stuff may not work properly on your Mac under Sierra and you should be reporting bugs and issues to Apple via the Feedback Assistant. You will have also been prompted to use Time Machine to back up your Mac before installing the OS – if you didn’t then give yourself a slap.
If you now can’t play because you opted into the beta program may I suggest you wipe and reinstall El Capitan on your Mac. Alternatively you could install El Capitan/Yosemite/Mavericks onto an external drive and play the Sims on there. Or you could wait until Apple release updates and hope your game works again. Even when Sierra is finally released in a few months time there is no guarantee that EA will support it.
No 3rd party apps are supported under beta versions of any operating systems. Maybe next time stick with the stable OS you are already running?
I love El Capitan. My Macs are lovely and fast thanks to Apple’s little tweaks to speed everything up and of course Metal, which my MacBook Pro can take advantage of. Amazing.
But do The Sims 3 and The Sims 4 love El Capitan? Yes and no.
As soon as I clicked on Into The Future to launch Sims 3 the debug error popped up:
Tried it a few more times, no joy. So I tried bypassing the Launcher, same thing happened. Purged RAM, re-patched 1.67 and restarted. Nothing. Then I decided to follow my own advice and move out the Sims 3 folder and let the game regenerate a new one – it worked! The lovely Tremayne4260 pointed out that the same thing happened to her when she upgraded to Yosemite last year and she had to reinstall all her Store content. So I copied over my Store content from the old Downloads folder into the newly created one, opened the Launcher, selected everything then hit install. It worked, everything installed, all 3.5 Gb of it. I then moved over my Saves and everything is hunky dory again. Sadly there doesn’t seem to be any improvement in gameplay though but at least I can play.
I clicked on the Sims 4 icon to open it, Origin opened and immediately my Mac asked me if I was sure I wanted to open it as it hadn’t been opened before. Yeah, whatever. I clicked yes then had to enter my password for the Origin Helper Tool (why does that always pop up??) then Origin crashed. So I opened Origin on it’s own. After several attempts at logging in and more crashing later I finally managed to open it. I then quit it and launched Sims 4 from the icon in my Dock. Everything opened happily, super quickly in fact. I then started to play my Sim and wow, everything is smoother, quicker and lag free. The game has really ramped up a level on my trusty 2012 15″ MacBook Pro.
We have a thread for each game on the official forums for feedback and any possible issues that may arise. It already looks like there may be an issue with late 2012 21″ iMacs with the NVIDIA GeForce GT 640M 512 MB graphics. Please post if you are experiencing difficulties, EA are aware of them –
The Sims 3: http://forums.thesims.com/en_US/discussion/856422/el-capitan-and-the-sims-3
The Sims 4: http://forums.thesims.com/en_US/discussion/856370/os-x-10-11-el-capitan-official-release-thread