What is the exception that makes to throw a Task.ThrowIfExceptional?

Question

I have a windows forms app developed with C# and .NET Framework 4.0 running Task.

I'm sorry to ask this question but I don't know where an exception occur. This is the stack trace:

One or more errors occurred.
   at System.Threading.Tasks.Task.ThrowIfExceptional(Boolean includeTaskCanceledExceptions)
   at System.Threading.Tasks.Task.Wait(Int32 millisecondsTimeout, CancellationToken cancellationToken)
   at MyCompany.Dispositivos.Plugins.TICAnKorr.DeviceTICAnKorr.StopLive()
   at MyCompany.Dispositivos.Plugins.TICAnKorr.VisorTICAnKorrMini.StopRemote()
   at MyCompany.Dispositivos.InterfazDispositivos.ICBaseVisor.DesasociarDispositivo()
   at MyCompany.Dispositivos.InterfazDispositivos.ControlMosaico.DesasociarTodosLosPaneles()
   at MyCompany.Dispositivos.InterfazDispositivos.ControlMosaico.CrearControlSeleccionado(DeviceBase device)
   at MyCompany.Dispositivos.InterfazDispositivos.ControlMosaico.icPanelViewer_MouseDown(Object sender, MouseEventArgs e)
   at System.Windows.Forms.Control.OnMouseDown(MouseEventArgs e)
   at System.Windows.Forms.UserControl.OnMouseDown(MouseEventArgs e)
   at MyCompany.Dispositivos.InterfazDispositivos.VisorDeMosaico.mousedown(Object sender, MouseEventArgs e)
   at System.Windows.Forms.Control.OnMouseDown(MouseEventArgs e)
   at System.Windows.Forms.UserControl.OnMouseDown(MouseEventArgs e)
   at MyCompany.BasicInterface.Controles_Basicos.ICLabel.lblText_MouseDown(Object sender, MouseEventArgs e)
   at System.Windows.Forms.Control.OnMouseDown(MouseEventArgs e)
   at System.Windows.Forms.Control.WmMouseDown(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.Label.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
Object reference not set to an instance of an object.
   at MyCompany.Dispositivos.Plugins.TICAnKorr.VisorTICAnKorrMini.MensajeEstado()
   at MyCompany.Dispositivos.Plugins.TICAnKorr.VisorTICAnKorrMini.m_DispositivoAsociado_NewResult(Object sender)
   at MyCompany.Dispositivos.ConexionesDispositivos.NewResultsEventHandler.Invoke(Object sender)
   at MyCompany.Dispositivos.ConexionesDispositivos.DeviceBase.OnNewResult()
   at MyCompany.Dispositivos.Plugins.TICAnKorr.DeviceTICAnKorr.HiloCaptura()
   at MyCompany.Dispositivos.ConexionesDispositivos.DeviceBase.<StartLive>b__9()
   at System.Threading.Tasks.Task.InnerInvoke()
   at System.Threading.Tasks.Task.Execute()

I think the exception thrown is this:

Object reference not set to an instance of an object.
       at MyCompany.Dispositivos.Plugins.TICAnKorr.VisorTICAnKorrMini.MensajeEstado()

What is the real exception?

If this is not the right place to ask this question, please tell me and I delete it.

I'm not asking about what is the meaning of Object reference not set to an instance of an object., I know it, I'm asking if this the exception that makes the task to throw a System.Threading.Tasks.Task.ThrowIfExceptional.

Answer 1

What happens when you execute an action returning a Task is that any exceptions get stored in the task's Task.Exception property.

When you call Wait, the code waits for the task to finish and then re-throws any exceptions that have occurred inside an AggreagtedException. So the ThrowIfExceptional method is being called after the task has finished to raise any exceptions that have occurred.

So likely the problem is a null reference in whatever code got executed to return the task being waited on. Should be something inside:

 MyCompany.Dispositivos.Plugins.TICAnKorr.DeviceTICAnKorr.StopLive()