Why am I getting this error:“Cross-thread operation not valid: Control lbFolders accessed from a thread other than the thread it was created on.”?

Question

This is baffling me, maybe somebody can shine the light of education on my ignorance. This is in a C# windows app. I am accessing the contents of a listbox from a thread.

Answer 1

Because you created a control in a thread and you're trying to reach it from another one. Call the InvokeRequired property as shown here:

private void RunMe()
{
    if (!InvokeRequired)
    {
        myLabel.Text = "You pushed the button!";
    }
    else
    {
        Invoke(new ThreadStart(RunMe));
    }
}