Question

Exception:

Object reference not set to an instance of an object.

Code:

    For Each p As Panel In Me.Controls.OfType(Of Panel)()
        arr.Add(p.BackColor.ToString())
        Me.Controls.Remove(p)
    Next

The line:

arr.Add(p.BackColor.ToString())

How can I fix this thing?

Answer 1

You probably declared arr something like this:

Dim arr As List(Of String)

You need to initialize the variable to an instance of List(Of String) before you can use it. Change it to:

Dim arr As New List(Of String)