'Unknown Error Occurred' when trying to download store content. (Mac)

Do you have expansions installed? If yes, please try this:

If you are having problems downloading items from The Sims 3 Store or The Exchange after installing World Adventures, High-End Loft Stuff, or Ambitions, it is likely that you did not patch your game prior to installing the expansions.

You must update your game before installing expansions or stuff packs.

In order to solve your issue, please follow the steps below:

1. Perform a manual uninstall of The Sims 3.
2. Reinstall The Sims 3 and update to the latest patch.
   It is important that you patch your game at this time to verify the patch is downloaded correctly.
3. Go to TheSims3.com and download an item from The Sims 3 Store or The Exchange.
4. Once you have verified you can download items from The Sims 3 Store or The Exchange, you can reinstall your expansions in the following order:
• Reinstall World Adventures
• Reinstall High-End Loft Stuff
• Reinstall Ambitions
• Reinstall Fast Lane Stuff
• Reinstall Late Night