World upload error 103

Hi, I recently made a modded 1.18.1 server with BOP, Quark, Tetra, and (much) more. However, the world I created was not generating BOP biomes, so I used mcaselector to copypast my base from the not-BOP world to a BOP-generated world. However, once I had done this it would not let me upload that file - other world files worked, but not that one. The error code it displayed was 103.

Things I've tried:

Re-generating a world, naming it world, then uploading

Uploading as folder

Uploading as ZIP

Hmm... I tried reloading the page, but 103 still kept coming up, I thought it might be additional aternos pages messing with reloading, but even with only one aternos page it wouldn't work.

I have tried generating the world a couple more times - it still won't accept my file. Is there anything that will work?

I've tried that a couple times. It works on my original world file, but not the mca edited one.

It worked! Thx so much!