Single Comment

Here's the source of your problem. You are playing your game with a preset that uses the Medieval Chess settings file that you are the author of. Since only the author may modify a settings file, I conclude that at some point, you modified this settings file to give the board one less rank, as per Travis Compton's request for changing the rules of the game. This caused there to no longer be any eleventh rank, which caused the space b11 to no longer exist. So when a piece tried to move from b11, Game Courier recognized the move as invalid. Since you caused the problem, you can also fix it. You can change your settings file back to how it used to be, then either delete your game or finish it. Once you're done with that, you can change the settings file back to how you have it now.