I had this problem and the solution that worked for me is as follows:
Note: Do not restart your computer until all steps are complete or it may break
Step 1: backup saves and mods you want to keep to a folder on desktop
Step 2: Delete the "The Sims 4" folder in C:\Users\(name of account)\Documents
Step 3: Delete "EADesktop" folder in C:\Program Files
Step 4: Delete "EA Games" folder in C:\Program Files
Step 5: Delete "EA Desktop" folder in C:\ProgramData
Step 6: Delete "Electronic Arts" folder in C:\Program Files
Step 7 Delete "Electronic Arts" folder in C:\Users\(name of account)\AppData\Local
Step 8: Delete "Link2EA" folder in C:\Users\(name of account)\AppData\Local
Step 9: Delete all shortcuts to sims 4 or the EA app
Step 10: Open windows apps and programs, select EA app, and click uninstall (if you do this before deleting those folders it will break)
Step 11: redownload the ea app installer off the website
Step 12: use the installer to install the EA app
Step 13: select download sims 4 and unselect all expansion packs to download (if you skip this step it will break)
Step 14: let the download finish and open the base game
Step 15: download expansion packs
Step 16: enjoy sims 4
Note: These steps have to be done in this order or it will break. I tried uninstalling before deleting those folders it broke, I tried downloading the packs with the base game it broke, I skipping the deletion of one of the mentioned files it broke. Why it only works in this order I do not know and I frankly feel like this has turned into some sort of arcane sims 4 summoning ritual but this has a 100% success rate on my machine and I'm not going to question it so long as it works