I get the following error message when I try to save my game
The Game failed to save. Error Code: 531:<long number>
Unclear, but it could be a corrupt object on the lot you are currently on or a bug caused by removing a sign on a retail lot.
Try switching to a different lot and save there. Be aware that if the problem occurs on a retail lot, all advances you have done are not saved. So if you hired someone, they will no longer be employees and stuff you added to the lot will not be there anymore.
EA is aware of the issue and working on a fix.