Board Thread:Modded Server Technical Support/@comment-26486187-20151024105628/@comment-27718380-20151024132106

Invalid session normally only happens to me if I change my skin or something, and MC is still open. Weird... I'll have a look on the Mojang forums to see if anyone else is having the same problems, although if it is something to do with mods - which to me is unlikely - it won't be found there.