Pistakilla said in Zombies "Incompatible UI version" - Custom games w/ friends:
Lionhearted1928
UI Compatibility Error
Since the update of r2107 people have been getting this error in T6 Zombies. This only occurs when players attempt to join their friends via custom games in DLC maps. A fix will be rolled out soon, please be patient!Possible solutions to try in the meantime:
Join at same time - You can use dvar zombies_minplayer x where x = amount of people required to join in order the game to start. You must type this before starting the match. Hopefully this will prevent the error.
This worked. As long as zombies_minplayers was used, and then xpartygo, me and my friends were able to play a custom game together.