Your Mac's Intel graphics are not supported in the game but it is interesting that you could play before in Yosemite. Please try editing the files as per the instructions in that linked thread. If that doesn't work do a complete uninstall then reinstall the base game, then manually patch and load the game to see if it works. Install each subsequent EP, testing to see if the game works after each one. You may find that you can play again but Late Night and Ambitions may make the game unplayable.
Responding because Ambitions and Late Night are exactly the ones that are affected... After one of my many uninstalls I added Late Night first and that actually worked... However all expansion packs installed after rejected me with my issue of "unknown error occurred" I checked and have the same intel graphics installed.. so i can only assume thats the problem.. Im trying to wait patiently for an update before I scream LOL
NVIDIA GeForce GT 650M 512 MB
Intel HD Graphics 4000 1536 MB
I think thats also what the initial poster had as well...
