Bodyshop was running extremely slowly and crashing halfway through loading, so I tried fixing it by applying GRM settings, and now it won't open at all and it gives me the 'application has crashed and will now terminate' immediately after clicking on it.
How can I fix this?

Can you post the Config log after running Bodyshop (text inside the file should say Bodyshop, not TS2 - the config log lists the last run program), a picture of your GRM settings, and your computer specs (CPU, RAM, graphics, etc.)?

Are you using a lot of CC? Some Bodyshop CC can cause crashes if clicked on, or when Bodyshop tries to load it. Large amounts of CC can cause slow loading/running. Best thing to try is to make sure Bodyshop loads fine and runs fine without CC (or with very minimal CC) before you start doing any changes, at least if it has been working before (?).

Bodyshop usually needs fewer things than the game - recognizing graphics + 4GB fix (not in GRM).

I don't have an error log because it freezes and crashes before I can even properly open it ☹️.

My cpu is Intel i7, I have 16gb RAM, nvidia 3060ti.

GRM have me 6009mb, which works great for my game.

I did take out my cc folder but I still can't open bodyshop.

I have the 4gb patch and it's working, is there a different way of applying it to bodyshop?

It's not an error log, it's a program running log. It usually gets updated even if there's a crash - "[computername]-config-log.txt"
It's in the Logs folder.

The log file shows if the game is reading GRM and the 4GB patch properly, among other things.

Have you deleted the cache files? Groups.cache, cigen.package, content registry and accessory.cache

The config log can be found in your Sims 2 folder under Documents as can the cache files. The Sims 2> Logs> config-log.txt.

I did find the log, my bad!
Here it is: https://pastebin.com/v5ySaajx
It looks like the 4gb isn't working for bodyshop, could that be it?
@joandsarah77 I did delete the cache files and that stopped it from crashing on opening, but it still freezes and crashes while loading.
This is as far as I get:

That's likely, yes.

Is your game installed in Program Files? If so, it's possible the 4gb fix isn't applying correctly if you're applying it directly to the file.
Try to copy the Bodyshop EXE file to the desktop, apply the fix there, and then replace the file with the fixed one. Easiest way to get around the admin privilegie issue (you usually get a prompt for admin approval when replacing the file, just click "yes").

That fixed it, thank you so much!

I also have the same problem, my Last EP is fun with pets I cant open body shop despite the fix suggested, (4gb, deleted cache, set GRM) and still no result of opening. I don't know why. and this file keep spamming.
[IMG][/IMG]
here is my config log after I apply the 4 Gb
[IMG][/IMG]

The file that spawns is a crash log (usually 2 files). Is there a text file too, or just the "mdmp" file?

Have you tried running Bodyshop without CC? Could be a piece of CAS CC that's causing Bodyshop to crash while loading.

Can't see it from the screenshot (it's further down in the config-log), but is the game reading your graphics?