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@r751mg1ujqu9 

As always make a backup of your game data before you start tweaking your game to have a fallback option if you don't like the result.

Try the following, to see whether your game works without mods:

1. Move all your mods and CC other than MCCC somewhere safe (there's no need to delete them!) such as a folder on your desktop so you can easily find them again.
2. Make sure to delete your localthumbcache.package file.
3. Once done, start up your game and test to see if the error still appears.

Your game will probably work flawless without mods. If that's the case you have to go through your mods and find the culprit. The 50/50 search might be a good method for this task to get a result in a reasonable time.

Attention:

All modded content will disappear from the game if you remove it, so if sims are wearing CC it will vanish while you're testing.

Because of this it's really important that you do not save the game while testing.

That way your CC will still be there when you bring your mods back into your game.

@r751mg1ujqu9  @Bonxie_MCCC 

Remember to also remove MCCC if you use it as it is frequently broken after a patch.

@jpkarlsen The current version is fine. Bonxie's used to using it for testing. (I tend to use Better Exceptions if I need a report with extra info, but either works.) Definitely worth testing without if it's not confirmed to be the current version, though!

@luthienrising 

The OP only mentioned downloading new mods and removing them again so had to assume that existing mods were not updated.

When I go into the game it tells me that there are no issues with my mods. I have completely gone through the mods and MC Command center last exception report. Everything is up to date. I even had curse forge double check the mods. I even updated curse forge. I am honestly confused on what it is. Is there anything that I could show or send into this discussion that might help you help me find the answer?

It is in a different language now, What do I do?

@r751mg1ujqu9 Up-to-date mods can still be broken. The only way to test if mods are causing your problem is this:

1. drag the Mods folder to your desktop (or rename it, but I prefer getting it cleanly away so I don't use the wrong folder later)
2. delete the file called localthumbcache
3. restart the game.

If you want to do an even fuller test, you can do this:

1. drag the whole The Sims 4 folder to your desktop
2. restart the game

If your game is still showing you errors at step 3 (in the first list) or 2 (in the second list), please let us know. If the only error is that the game is in the wrong language for you, that's a tech issue not mods, so please let us know if you're PC or Mac. But test with no mods first. There's no tool that can do this for you, and there's no tool that can show you all possible mod causes of a problem.

I don't have a folder called localthmbcache. I do have onlinethumbcache, but it only has photos that show up on the home screen on the sims page. I have already done the test of removing the mods folder as I said in the first post and it came back working fine in English, but I( also removed each mod one by one and it was still broken. so unless you are trying to say all of the mods are broken I'm not sure what you are trying to get at. the MC Command center last exception report would have caught it, or even sims. It opens fine and nothing is getting flagged. Its just in a language I don't know now. 

@r751mg1ujqu9 

The localthumbcache.package is a file not a folder it is in the same folder that has the mods and saves folders plus other folders and files.

I just checked. I do not have anything in there by that name.