Game unable to open on dx9 but works on dx11

kosmosjoon​  Check your antivirus for any recent actions involving Sims 4.  The DX9 and DX11 versions use different executables: TS4_DX9_x64 and TS4_x64, respectively.  So one can be blocked while the other is allowed through.

If that's not the issue, try reinstalling DirectX 9.  I previously described how to do so here:

Re: Sims 3 launcher won't open | EA Forums - 8260715

puzzlezaddict​ My antivirus looks clear, nothing was found. I ran perfmon /rel and it said something about the ITS service? I attached a screenshot. I also tried reinstalling DirectX 9 following the instructions but it still doesn't work :(

I also ran dxdiag

kosmosjoon​  I unfortunately can't download your dxdiag or view your screenshot.  It's a problem with this website, not sure what exactly, but I've reported it.  If you want, I can keep checking your thread to see when it's resolved.  Or if you'd prefer, you can upload the dxdiag and screenshot to a third-party filesharing site (Google Drive, Dropbox, etc.) and link them here.  Or you can send me the link via PM.

If you use Google Drive, make sure anyone with the link can view the files.

I'll PM you the link!

kosmosjoon​  Now that you've sent the info, this site is allowing us to view uploads again.  So you can take down the Google Drive uploads if you want.

Your dxdiag lists one crash of LNBITSSvc.exe, which is a Lenovo service that's probably not causing problems with Sims 4, and one actual Sims 4 error from DirectX 11 mode.  The other errors point to a component of the Windows device registration service, which likely isn't relevant either.  It's possible that these have crowded out any Sims 4-in-DX9-mode-related errors, especially if you've been playing in DX11 mode for a while.  It's also possible that there are no proper DX9 errors.

What I'd like to see now is whether you can trigger a crash in DX9 mode that creates a crash dump.  Switch to DX9 mode through the EA App or Steam (here's how, except with -dx9 rather than -dx11), try to start the game, and let it fail.  Click Windows key-R and copy and paste this:

%LocalAppData%\CrashDumps

When you enter, you'll see a list of .dmp files.  If one of them is from Sims 4 or the EA App, please upload it to Google Drive and link it here, or send me the link via PM.  If you see a crash dump that was written at exactly the time the game crashed, I'd like that too.  But in either case, please only upload files from after we started troubleshooting here.

If there is no Sims 4 .dmp file, you can enable them:

• Hit the Windows key, type "command prompt" in the box, right-click on Command Prompt in the search results, and select Run as Administrator
• In the window, paste "reg add "HKLM\Software\Microsoft\Windows\Windows Error Reporting\LocalDumps\devenv.exe" /v DumpType /d 2 /t REG_DWORD" without the outside quotes into the box, and enter
• Launch Sims 4 and wait for it to crash (whether you can play at all or not)
• After it crashes, wait for any crash dialogs to finish
• Then hit Windows key-R and paste "%LOCALAPPDATA%\CrashDumps" without quotes into the box, and enter
• Upload the last .dmp file and provide the link
• When you want to undo the auto crash log dumps, open Command Prompt as before, paste "reg delete "HKLM\Software\Microsoft\Windows\Windows Error Reporting\LocalDumps" /f" without the outside quotes, and enter.

I PM'd you the link to the Google Drive with the crash dumps. There was one from when it first crashed so I included that as well