Mods that change the map prevent you from creating a world

Hi, I'm trying to play a mod in host mode with a friend on version b42.0.4, but I'm getting an error. The mod changes the map to a custom one. Ever since b42 came out, we haven't been able to play. I checked this forum and only saw issues with the game crashing, but no one is talking about this. No mod that changes the map has let us play. I asked on Discord, but they told me everything was fine