Solution to “System.Data.InvalidConstraintException: ForeignKeyConstraint” error

If you encounter the following error: System.Data.InvalidConstraintException: ForeignKeyConstraint FK_foreign_key_name requires the child key values (-1) to exist in the parent table. Or The INSERT statement conflicted with the FOREIGN KEY constraint "FK_foreign_key_name ". The conflict occurred in database "YourDatabase", table "dbo.Tablename", column 'YourPrimaryKey'. The statement has been terminated. Probably you are using a Parent-Child table or Master-Detail table. This error occurs if you have a parent-child form with a Details form and a DataGridView control. The errors above will pop-up after you try to save your record. The solution to this is to issue an EndEdit command before you try to edit your child/DatagridView control. You can do this, for example, in the GotFocus event of your DataGridView control like: