I'm having the exact same problem! I can't figure out what's wrong for the life of me ... I just deinstalled and reinstalled everything but still the same issue. Help! :(
Change the name of the sims 3 folder in Electric Arts one (Documents/Electric Arts/ The sims 3) into something like 'The sims 3 Old', l', and then open the launcher for the game - it should create a new 'the sims 3' folder automatically. Try to play the game. I did it it worked and i left the game and came back to make sure it still worked and it did. Hopefully, this helps you
Thank you so much for this answer. I haven't been able to play my Sims 3 for a while. This fixed it right up.
