Listbox + Background Worker (Cross thread problem)

[Inferrd]

You know, I swear before you edited your code, you had

Dim ItemSelection = ListBox1.SelectedItem

declared at Form level, outside the BGW's DoWork event handler.

Of course it will give problems referencing the ListBox inside the DoWork event handler, as that runs on a thread that is not the UI's thread and so you can't access any Form's Controls in there.

In any case, I prefer Ian's solution of passing the value as an argument rather than accessing a (disappeared) global variable