This has happened to my last 2 playthroughs on Steam version.

Basically i play for many years, build up my fort and it gets to a point where i save the game and the game crashes out during saving.

Here is my latest game which loads fine but if u allow the date to proceed one more day and then try to save the game it will crash.

Obviously this issue means i cannot play the game anymore. I am not wasting my time building another fort which will fail in the future.