“Installation Error” When Joining Server. Help Please

[noddynod443]

Hey guys, I finally got around to installing joint ops, esc, and the aw2 mod all fully patched on some of my LAN party computers.

However, I tried hosting fron in-game a co-op map, and then tried joining to it from a difference pc. I get this error when trying to join:

“There is an installation issue. Please ensure you are running the latest consumer version. (GDCO12)”

Does anyone know how to fix this error please?