How to Fix "Fatal Error" in Elden Ring Seamless Co-op Mod

[@putdomilliona]

I have the exact same problem bro (I installed version 1.15, there was no such problem, but it was impossible to play with friends there, there was an error: k_esteamerror and something else, I now installed version 1.12 as many advised, and here is such an error

[@1._._._._._._._._._._._._._._z]

I have the same problem, did u fix it?