[RESOLVED] Unhandled exception on form closing

[jculpepper]

I have a simple form that when filled out with a case # will return the name of the person that is handling the case. I am getting an error on any machine that does not have VS 2010 installed on it. The error is when ever the user uses the close button (the red X) at the top right of the form the following error is generated:

System.InvalidOperationException: Collection was modified; enumeration operation may not execute.
   at System.ThrowHelper.ThrowInvalidOperationException(ExceptionResource resource)
   at System.Collections.Generic.List`1.Enumerator.MoveNextRare()
   at System.Collections.Generic.List`1.Enumerator.MoveNext()
   at Microsoft.VisualBasic.PowerPacks.ShapeCollection.Dispose(Boolean disposing)
   at Microsoft.VisualBasic.PowerPacks.ShapeContainer.Dispose(Boolean disposing)
   at System.ComponentModel.Component.Dispose()
   at System.Windows.Forms.Control.Dispose(Boolean disposing)
   at System.Windows.Forms.Form.Dispose(Boolean disposing)
   at Case_Info_Application.Form1.Dispose(Boolean disposing)
   at System.Windows.Forms.Form.WmClose(Message& m)
   at System.Windows.Forms.Form.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Here is the code for the form itself:

Imports System.Data.SqlClient

Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click

        Dim user As String = logon.user
        Dim pword As String = logon.pword

        Dim con As New SqlConnection(...)


        Dim i As Integer = 1
        Dim casenumbers As String

        If InStr(TextBox1.Text, "ME") Then
            casenumbers = TextBox1.Text
        Else
            casenumbers += "', '" & TextBox1.Text & "ME"
        End If
        If TextBox2.Text <> "" Then
            If InStr(TextBox2.Text, "ME") Then
                casenumbers += "', '" & TextBox2.Text
                i += 1
            Else
                casenumbers += "', '" & TextBox2.Text & "ME"
                i += 1
            End If
        End If
        If TextBox3.Text <> "" Then
            If InStr(TextBox3.Text, "ME") Then
                casenumbers += "', '" & TextBox3.Text
                i += 1
            Else
                casenumbers += "', '" & TextBox3.Text & "ME"
                i += 1
            End If
        End If
        If TextBox4.Text <> "" Then
            If InStr(TextBox4.Text, "ME") Then
                casenumbers += "', '" & TextBox4.Text
                i += 1
            Else
                casenumbers += "', '" & TextBox4.Text & "ME"
                i += 1
            End If
        End If





        Dim sql As New SqlCommand(command, con)
        Try
            con.Open()
            Dim reader As SqlDataReader
            reader = sql.ExecuteReader
            Dim sArray(i - 1) As String
            Dim x As Integer = 0
            While reader.Read

                sArray(x) = reader.Item(1).ToString
                x += 1
            End While
            Label1.Text = sArray(0)
            Label1.Show()
            If TextBox2.Text <> "" Then
                Label2.Text = sArray(1)
                Label2.Show()
            End If
            If TextBox3.Text <> "" Then
                Label3.Text = sArray(2)
                Label3.Show()
            End If
            If TextBox4.Text <> "" Then
                Label4.Text = sArray(3)
                Label4.Show()
            End If


            casenumbers = Nothing
        Catch ex As Exception
            MsgBox(ex)
        Finally
            con.Close()
            con.Dispose()
            sql.Dispose()
        End Try


    End Sub


    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
        Label1.Hide()
        Label2.Hide()
        Label3.Hide()
        Label4.Hide()
    End Sub

    Private Sub Button2_Click(sender As System.Object, e As System.EventArgs) Handles Button2.Click
        Try
            Me.Close()
        Catch ex As Exception
            MsgBox(ex)
        End Try


    End Sub

    Private Sub Button3_Click(sender As System.Object, e As System.EventArgs) Handles Button3.Click
        Me.Close()

    End Sub
End Class

The only collection that I see is the string array (sArray). I read that this issue occurs when the list is changed while being looped through but I don't see that here. Any Help?

[Shaggy Hiker]

I don't see it either, and I'm not sure that it would or could happen with an array anyways.

I see a mention of VBPowerPacks. Does that mean anything to you? Are you using something from that? It certainly sounds like something isn't getting copied correctly on installations, and I have some vague memory of people having other issues about this when using VBPowerPacks incorrectly.

[jculpepper]

So just in case someone else has this problem here is the solution. For some reason the forms were not disposing of the shape collections correctly.
Option one is to remove anything that uses the visual basic power pack 10.0.
Option two is to insert this function at the top of the form designer code where the dispose sub is called. Make sure you adjust the statement for all of your shape containers. (shapecontainer1, shapecontainer2, etc..)

Protected Overrides Sub Dispose(ByVal disposing As Boolean)
    Try
        If disposing Then DisposeShapeContainer(ShapeContainer1)
        If disposing Then DisposeShapeContainer(ShapeContainer2)
        If disposing Then DisposeShapeContainer(ShapeContainer3) ', etc...
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
    Finally
        MyBase.Dispose(disposing)
    End Try
End Sub
Protected Sub DisposeShapeContainer(ByVal AShapeContainer As Microsoft.VisualBasic.PowerPacks.ShapeContainer)
    If AShapeContainer IsNot Nothing Then
        If AShapeContainer.Shapes IsNot Nothing Then
            Dim tshapes As New Generic.List(Of Microsoft.VisualBasic.PowerPacks.Shape)
            For Each tshape As Microsoft.VisualBasic.PowerPacks.Shape In AShapeContainer.Shapes
                tshapes.Add(tshape)
            Next
            AShapeContainer.Shapes.Clear()
            AShapeContainer.Shapes.Dispose()
            For Each tshape As Microsoft.VisualBasic.PowerPacks.Shape In tshapes
                tshape.Dispose()
            Next
        End If
        AShapeContainer.Dispose()
    End If
End Sub

[jculpepper]

Here's where I found the information I just posted:
http://channel9.msdn.com/forums/Tech...Shape-Dispose/

[Shaggy Hiker]

Good that you solved it, and thanks for posting the solution.