I get an error everytime I join a server

[twilit hill]

Whenever I try and join a public server I will always get an error along the lines of "You are missing this file" or "This file doesn't match with the server" I have installed modpacks, uninstalled the game, restarted everything but nothing works, the only servers I can join are ones hosted by my friends where I just press join game on their profile.

I can get into a server but as soon as I get past character creation I get that

[dawn plaza]

#mod_support