@CORATHESIMMods can impact that, but only briefly in most cases. Try this:
On the EA APP \ Manage \ make sure the expansion is showing as downloaded. ( and for correct system type )
Repair the game
If not working then:
Remove the mods \ trays \ saves to desktop or rename the folder ( see below )
Repair again and start a new game and sim to test.
If all is well, you can add mods \ trays \ saves back
I recommend using 50 / 50 so you can avoid issues with mods.
TO RENAME:
~Close the game
Rename Documents\Electronic Arts\The Sims 4 to Documents\Electronic Arts\The Sims 4_Old
Repair the game
Start the game. All your content will be gone now as the game created a new folder. All your saves/.. is still in the old folder so not to worry
Start a new save game
Check if you still have the error
Report back with your results for further steps on how to get your stuff back.~ quote from crinrict
Also check your mods are up to date and not broken. https://answers.ea.com/t5/Mod-CC-Issues/Broken-Obsolete-and-Updated-Sims-4-Mods-1-104-Jan-16-2024-Game/td-p/13400494 and on Deaderpool's DISCORD
FINALLY, if you purchased the pack from a valid source and no help above reach out to EA SUPPORT https://help.ea.com/en/help-home/
