Question : FormClosing causes mscorlib.dll "Index was out of range exception".... why

I have a windows forms application written in vb.net. All of a sudden I am getting an exception that does not make sense to me.

I have a main form. From this main form I open anotherform using form.ShowDialog()
From this form I then show another form also using form.ShowDialog as I want each one to be the child of the previous form.
I then have a Form Closing event from the last opened form that updates a datagridview with a value but I then get an Index out of range.

I have verified that the row index is correct, however I can see that the datagridview says it only has 0 rows when it actually has 2. So when I try to update row One index it crashes.

This seems to be a UI issue. Any thoughts?

Answer : FormClosing causes mscorlib.dll "Index was out of range exception".... why

You can alleviate this problem greatly by passing in the "parent" form to ShowDialog() like this:

                       
         
           
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             Public Class Form2

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim F3 As New Form3
        F3.ShowDialog(Me) ' <-- passing in the current instance of Form2 to our dynamic instance of Form3
    End Sub

End Class

Public Class Form3

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        ' cast the "owner" to the actual instance of Form2 so we can use it:
        Dim F2 As Form2 = CType(Me.Owner, Form2)
        F2.Text = "Can you hear me now?"
    End Sub

End Class

           
         

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