Comments by Asha Love (Top 7 by date)

It really worked. Thank you. I have not encountered anything like this before. Although the true value was not given for e.Cancel, but by putting the code e.Cancel = false; At the end of the FormClosing form, the program was closed without any problems.
thanks guys

The form that contains the gridview is the child form.
Exactly when this happens, the parent form is not closed.
The source of all these problems is Gridview. When a cell is clicked and that cell is edited, the problem is solved.
Sorry if I can't explain better, my English is poor.

private void Frm_FormClosing(object sender, System.Windows.Forms.FormClosingEventArgs e)
{
if (System.Windows.Forms.MessageBox.Show("Are you sure?", "", System.Windows.Forms.MessageBoxButtons.YesNo) == System.Windows.Forms.DialogResult.No)
{
e.Cancel = true;
return;
}
}

private void Frm_FormClosed(object sender, System.Windows.Forms.FormClosedEventArgs e)
{
System.Windows.Forms.MessageBox.Show("Test");
}

No error occurs. Form does not close when the X button is pressed.
But the X button works when a cell is clicked to enter edit mode