The value of each cell must be found in the list of drop-down menus, otherwise an error will occur, and there is no good way to process it. About adding a new record in the DataGridView can add a line record in the data sheet bound to the column during Form Load, which corresponds to the default value of the DataGridView to add a new record, so that you can guarantee that you can in List This value is found. However, this is not the best practice, I hope I can find a way to deal with the value that is not found in the list, should there be an event to handle this state? I haven't found it yet.
