On Factorio .15.25 the use of this mod causes players to be disconnected from the game after loading the map with a crc mismatch error for the connecting player.

Disabling the mod does not help for already created saves however if you make a new game with the mod disabled players can join fine.

Any ideas of a fix?

Edit: Same issue with saves not loading with version .15.9)

Edit2: Turns out if he hosts the map I can connect just fine so I guess its some sort of issue with my Factorio.

just a guess but maybe both of you delete and redownload the mod from the site again? Sounds like one of the files are corrupt and won't let him join. I had similar problems when i was tweaking a few files in a different mod to work around an error