I have a similar problem.
Error: InvalidStateError, Script: http://atwar-game.com/java/atwar.core.min_v13.js, Line: 158, Column: 395, StackTrace: undefined
Error: InvalidStateError, Script: http://atwar-game.com/java/atwar.core.min_v13.js, Line: 158, Column: 395, StackTrace: undefined
Error: InvalidStateError, Script: http://atwar-game.com/java/fabric/fabric.min.js, Line: 388, Column: 1, StackTrace: undefined
I've played my scenario on normal, just fine, everything worked. I started a casual game and on turn 2 it wont let me in, it gets stuck on "Finalizing". Cant even play the scenario I created and started.