A fatal error has occurred, connection has been terminated

When ever I join the server it kicks me the second after I join and says "A fatal error has occurred, connection has been terminated" I've seen a lot of other people ask for help with this same problem but I can not figure out what mod is causing the problem! Please help!

I removed every single mod and it is now working, I will have to add them back one at a time.

I put back in every single mod and it works now...