Modding error "player X is not running the same version of the data file"

Hey guys. For a civilisation mod i've been making, I have been running into issues in multiplayer where it says "player X is not running the same version of the data file", when they very clearly are. I will update the mod, both of us will delete the version of the mod we had, resubscribe and load up the game, but the issue persists. There was one time we did not get the error but we cant see any difference between that time and all the others.