I am on turn 255 of my first game, and whenever I hit the end turn button it never stops 'pending'. I have attempted reloading to several saves beforehand and it still will not fix the issue. I also tried starting a new game, but the same error is now popping up there too. 

I have no idea how to fix this nor what caused it, so I realized my best course of action would be to go right to the top.