Oatmealman

im getting erros just like this (the numbers are different) Im playing a slightly altered better minecraft modpack, i can play SP just fine with no issues. i copied the modpack to my laptop for my son. if either of us opens a world to lan the other cannot join, with this error popping up. doesnt matter who 'hosts', neither of us can join the other. i can find NO solutions at all. we are both frustrated. how can i get a log to post?