WPF Dispatcher throws TargetInvocationException

Question

I have a problem with my debugger, when faulty code is executed in the UI Thread the debugger correctly points out the faulty line, same when this is executed inside a thread, but it behaves kind of weird when called inside a dispatcher : TargetInvocationException is thrown in the disassembly.

How could I have it displayed properly and avoid this annoying message?

Here is a simple example that illustrates the problem:

private void Button_Click_1(object sender, RoutedEventArgs e)
    {
        //navigator.NavigatToMenuAccueil(true);

        //Throws NullPointerException
        /*String x = null;
        String y = x.ToUpper();*/

        Thread th = new Thread(DoWork);
        th.Start();
    }

    private void DoWork()
    {
        //Throws NullPointerException
        /*String x = null;
        String y = x.ToUpper();*/

        Thread.Sleep(1000);
        Dispatcher.BeginInvoke(new Action(() =>
        {
            //Throws TargetInnvocationException 
            /*
            String x = null;
            String y = x.ToUpper();
             */

            MyTextBlock.Text = "My New Text";
        }));            

    }

Answer 1

TargetInvocationException is the exception that is thrown by methods invoked by reflection ( according to MSDN ), and by using BeginInvoke , you are telling the Dispatcher to do that.

Any exception that is thrown inside the passed delegate is wrapped in a TargetInvocationException . You can't prevent the Dispatcher from wrapping the original exeption. You can still get at the original exception by accessing InnerException though.