C# Cross-thread operation not valid [duplicate]

Answer 1

You should Invoke backgroundWorker1.ReportProgress(1);, because only UI thread can directly access UI controls. Example of invoking:

private delegate void AddListBoxItemDelegate(object item);

private void AddListBoxItem(object item)
{
   if (this.listBox1.InvokeRequired)
   {
       // This is a worker thread so delegate the task.
       this.listBox1.Invoke(new AddListBoxItemDelegate(this.AddListBoxItem), item);
   }
   else
   {
       // This is the UI thread so perform the task.
       this.listBox1.Items.Add(item);
   }
}