In reply to ApolloxYT:
I had a similar problem.
All my mods that DID work previously ended up giving me this exit message.
I updated everything and reinstalled everything and wanted to punch a hole through my monitor because nothing seemed to work.
I ended up getting them to work, but maybe not exactly "fixed" per se..
The problem was.. that I had everything running on the latest versions.
I rolled back the mod be on 1.20.1, instead of the current 1.20.4, and then rolled back the forge to its previous version as well, and now everything is working fine again.
They'll probably fix it eventually, but I guess just don't use the recent patches because they seem to be flawed.