MC Eternal Crash

Hello! I have a MC Eternal 1.6.1 and randomly crash with this error:

A mod is doing something asynced to minecraft and minecraft itself is complaining about it.

Sadly dont know what mod it is so i would advise doing a binary search for it

How can I do that?

Binary search?

Simply take half your mods, if the issue persists then you know its one of the mods in that half. If it doesnt, then its in the other half.

Ahh, this crash happens randomly, unfortunately there is no fixed point