lose connection when starting a game

[Issilrah]

hello, the world map doesnt run, the game keeps droping me when i try to start a campaign and on the server i get this message: Actor asset not found, Method: Generate() - Generate() in WorldGenerator.cs:341 any idea how to solve it or what am i missing?
how can i downgrae to version 2.7.4.84161
im actually trying to log in with the 2.7.7 wich is the one i donwloaded from blizzard... how to download the exact version i need for thew game to work? any links please? thank you