MySQL: Foreign key error?

Question

MySQL

I am writing a client in C# for a database on MySQL (connection via mysql.Net connector) I encountered such a problem.
Given are reference tables and a pivot table.
For example, one of the directories Counterparties

, add a new counterparty to it,

the code of the save button

try
            {
                this.Validate();
                this.contragentBindingSource.EndEdit();
                this.tableAdapterManager.UpdateAll(this.contractDataSet);
                this.contractsDataGridView.Update();

                MessageBox.Show("Данные обновлены успешно!", "Договоры", MessageBoxButtons.OK, MessageBoxIcon.Information);
            }
catch
            {
                MessageBox.Show("Ошибка обновления данных!", "Договоры", MessageBoxButtons.OK, MessageBoxIcon.Error);
            }

The agent is added to the mysql table normally)
now, we want to correct the existing contract, or edit the existing one, by selecting the newly added counterparty
for which, when saving the data, an error occurs

. If you relogin to the client and select the counterparty, then everything works fine.

Answer 1

I didn’t write clients in C#, but are you sure that the transaction is committed when a new counterparty is added?

Answer 2

Make a request to edit the contract, see what data they want to insert, then see if there is a foreign key in the database with which you are trying to add a record.
Look for inconsistencies there, but most likely, as already said, the transaction commit does not go through until the exit from the client.