My friend is trying to join my island after i invited him, but it won't work. It says "Internal error while trying to perform that command". How can we get around that. The Devs won't help. The mods won't help. We tried to leave game and join again. Nothing will work. We tried making him kick all of his coop partners, and tried everything else. What will work?

 

that happens with me to I have the same question

 

Your friend has to restart his island first.
He does that with /newisland replace

 

he didn't have a island

 

We did /newisland replace

 

What i think you have todo is coop inivte well i think he has todo this commands this is wut u do
/coop invite <player>

Your friend accept le coop /coop accept

 

if you need more help just /coop
or if you going to leave ur friends island or restart first do /coop leave
then /newisland

 

We did all that

 

This has happened to me several times, everytime it was because their name was misspelled.