Unable to open sims4: Game Data missing error

im having this same issue.. and i dont even use mods? I also uninstalled the entire game and reinstalled.. and stil having the issue?? ☹️

@southernxbarbie  Do you use a third-party antivirus?  If so, please disable it temporarily and clear the EA App's cache:

https://help.ea.com/en/help/faq/clear-cache-to-fix-problems-with-your-games/

Then repair the game (again): open My Collection, hover over the Sims 4 icon, click the three dots, and select Repair.

If that doesn't help, please uninstall Sims 4 again, clear the App's cache again, and restart your computer.  Create a new folder on the drive of your choice where you want Sims 4 to be installed.  Put that folder on the root level of the drive, for example C:\Games is fine, but C:\Program Files\Games is not.  Open the EA App and install Sims 4 into this folder.  If you do have a third-party antivirus, leave it disabled while the game is installing, and don't reenable it until you've tried to play at least once.

i just use what my computer has.. 

@southernxbarbie  Okay, but please try uninstalling and reinstalling into a new folder, as I described.

@southernxbarbie  Alright, I think it's time to clean everything out, specifically with Revo Uninstaller (it's free).  Start with Sims 4:

• Put aside your Sims 4 folder in Documents\Electronic Arts, if you have one, and rename it to something that doesn't include the words "Sims 4."
• Download Revo Uninstaller (the free version is fine) from here.
• Launch Revo, select Sims 4 from the list, and click Uninstall.
• Once the game is uninstalled, select "Moderate" under "scanning modes," and click Scan.
• Review the list, in case there's something you want to save; otherwise, click Select All, and then Delete.
• Close Revo, and restart your computer.

Next, uninstall the EA App with Revo as well.  I don't have a specific guide for the App, but it should be straightforward.

Before reinstalling anything, create a new admin Windows account on your computer.  Make it a local account, as in, don't sign into Microsoft, and don't sync with any other services you normally use.  You'll be installing everything through this account.

Instead of reinstalling the EA App, see if you can install Origin:

https://answers.ea.com/t5/Origin-Client-Web-Technical/Downloading-and-installing-Origin-Windows-and-Mac/m-p/11915666

If you can run it, install Sims 4 there, and please install it another new folder, again on the root level of the drive of your choice.  If Origin won't work and just forces you to download the EA App, that's fine; here again, install Sims 4 into a new folder.  You can install only the base game, to save time, if you want.