Getting lots of errors after 4.21, anyone know why Im getting these?

I suddenly seem to be getting lots of errors with blueprints communicating with each other ,They don’t seem to be affecting anything but always pop up after I exit.
I cant really tell from the messages why though?

I just want to confirm that I also got errors in AnimBP - Accessed none for valid and existing variables.
For instance: Cast to VehicleBP -> steering_wheel (static mesh) and got steering wheel is not valid. Earlier it was working without problem.