There's a problem with your game's setup W10

jazzman_87  Are you getting exactly this error, or a different one?  If it's different, please type out the text or post a screenshot.

In either case, please please provide a dxdiag.  Hit Windows key-R, enter dxdiag in the run box, wait for the scan to finish, click "Save all information," and save the file to your desktop.  From there, you can attach it to a reply using the camera (Insert Media) icon included with the other formatting buttons.

jazzman_87  I've split your post into its own thread since you have a Windows 10 computer, not Windows 7 like most people with this error, so the cause is likely different for you.  Your dxdiag lists a few generic Windows errors, so please run a couple of basic checks of your Windows system files:

• Hit Windows key-X
• Choose either “PowerShell (Administrator)” or “Windows Terminal (Administrator),” whichever option is offered
• Inside the window that appears, copy and paste “DISM.exe /Online /Cleanup-image /Restorehealth” without quotes, and enter
• The system will start validating soon. If it throws an error, please list it here
• After it reaches 100%, hit Windows key-X again
• Again, choose “PowerShell (Administrator)” or “Windows Terminal (Administrator)”
• Inside the window, copy and paste “sfc /scannow” without quotes, and enter
• Post the message you receive here

Restart your computer, hit Windows key-i, select Update & Security, and click the box to check for updates.  If any install, restart again afterwards.

If you use a third-party antivirus, please disable it, temporarily of course.  Clear the EA App cache:

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

and repair the game, again if you have already: game library > Sims 4 > Manage > Repair.  Then try to play with the AV still disabled; as long as you don't do anything else at the same time, your computer should be safe.  If this works, set exceptions for TS4_x64 and TS4_Launcher_x64, and EADesktop.exe as well, in your AV.

If this doesn't help, please list the location where you've installed the game, which you can see under Sims 4 > Manage > View properties.  That's also where you'd add the -dx9 command line argument if you're playing through the EA App.  In Steam, it's Properties > General > Launch options.

jazzman_87  Please try doing a clean uninstall of Sims 4 and the EA App.  (Steam is likely fine, and uninstalling it would also uninstall any other Steam games you have.)  Instructions are here:

https://answers.ea.com/t5/PC/CURRENT-ISSUE-Sims-4-DLC-shows-as-installed-won-t-load-in-game/m-p/12942151#uninstall

To keep things simple, I'd suggest reinstalling through the EA App and leaving Steam out of it for now.  Please do create a new folder, on the root level of your drive, into which you install Sims 4.

jazzman_87  Okay, so you've established that Sims 4 works on your computer, under some conditions.  The problem is that your Steam-owned DLC won't work in the EA App.  So please clean-uninstall the EA App version of Sims 4 and install it through Steam.

You can change the install location in Steam; it's just a bit more complicated than with the EA App:

https://help.steampowered.com/en/faqs/view/4BD4-4528-6B2E-8327

You don't need to apologize for the late reply or for the new post.  Lots of people don't have time to keep troubleshooting (or get distracted) and come back when they can.  And the whole point of this site, or the help sections anyway, is to keep asking until the problem is addressed.