No matter how many times I try the hats/Contributors folder can't be deleted from my server via FileZilla. Not sure if it's how the folder is generated from the mod, if not probably not on your end.

Closing all issues as Hats has been rewritten from the ground up and the old mod for a long time now was no longer supported.. I'm sorry I wasn't able to address your issue. If you're still playing modded Minecraft, consider checking out Hats for 1.16.5+.

File.mkdirs();

That's weird, I'll test it again later, it might just be the host, no idea.