EntityFramework.dll but was not handled in user code

Question

I have an error when i click on submit button

 

"An exception of type 'System.Data.Entity.Infrastructure.DbUpdateException' occurred in EntityFramework.dll but was not handled in user code

Additional information: An error occurred while updating the entries. See the inner exception for details."

 

i atteched my code blew, please help me out from this issue