Can't join my server

Hi! I just installed a Spigot server with Bungee Cord on! I'm going to make a community so I guess Bungee Cord is the best thing for this!

But let's get to the problem! When i'm trying to join it just says "Internal Exception: java.lang.ClassCastException: bit cannot be cast to fm"

I have tried to find something on google but nothing helpful!