VB.net: Object not set to an instance of object - vb.net

Question

I am getting a Object not set to an instance of object error. I have put a list view where all messages should be shown. I am using lumisoft sample code which I ported to vb.net
Private Sub FillMessagesList()
Me.Cursor = Cursors.WaitCursor
Try
Dim m_pPop3 As POP3_Client = Nothing
For Each message As POP3_ClientMessage In m_pPop3.Messages
Dim mime As Mail_Message = Mail_Message.ParseFromByte(message.HeaderToByte())
Dim item As New ListViewItem()
If mime.From IsNot Nothing Then
item.Text = mime.From.ToString()
Else
item.Text = "<none>"
End If
If String.IsNullOrEmpty(mime.Subject) Then
item.SubItems.Add("<none>")
Else
item.SubItems.Add(mime.Subject)
End If
item.SubItems.Add(mime.[Date].ToString())
item.SubItems.Add(CDec(message.Size / CDec(1000)).ToString("f2") & " kb")
item.Tag = message
ListView1.Items.Add(item)
Next
Catch x As Exception
MessageBox.Show(Me, "Errorssssss: " + x.Message)
End Try
Me.Cursor = Cursors.[Default]
End Sub

Answer 1

The problem is here:
Dim m_pPop3 As POP3_Client = Nothing
For Each message As POP3_ClientMessage In m_pPop3.Messages
You set m_pPop3 to Nothing and then try to access one of its members.
You say that you ported the code - perhaps you need to look back at the original code and port it correctly:
private POP3_Client m_pPop3 = null;
/// <summary>
/// Default constructor.
/// </summary>
public wfrm_Main()
{
InitUI();
this.Visible = true;
wfrm_Connect frm = new wfrm_Connect(
new EventHandler<WriteLogEventArgs>(Pop3_WriteLog));
if(frm.ShowDialog(this) == DialogResult.OK){
m_pPop3 = frm.POP3;
// etc...
}
private void FillMessagesList()
{
this.Cursor = Cursors.WaitCursor;
try{
foreach(POP3_ClientMessage message in m_pPop3.Messages){
// etc...
}
}
Notice that m_pPop3.Messages is a private member here, not a local variable as you have implemented it.
To correct your code I would suggest changing it to be more similar to the original. Change the local variable to a private member and set it in the constructor, just as the original C# code does.

Answer 2

The culprit is possibly from the code in the 2 lines:
Dim m_pPop3 As POP3_Client = Nothing
For Each message As POP3_ClientMessage In m_pPop3.Messages
You're trying to loop through the messages in "m_pPop3" but you've explicitly set it to nothing on the line directly above.

Answer 3

I'm guessing it's here since you're setting m_pPop3 to Nothing. If you'd stepped through the code it would show you that.
Dim m_pPop3 As POP3_Client = Nothing
For Each message As POP3_ClientMessage In m_pPop3.Messages