System.NullReferenceException

Question

Hi, I have a windows application developed in VS.NET 2003. sometimes I am getting System.NullReferenceException exception from CallWindowProc().

Here is the stack trace of the exception

Error_Stack_Trace : at System.Windows.Forms.UnsafeNativeMethods.CallWindowProc(IntPtr wndProc, IntPtr hWnd, Int32 msg, IntPtr wParam, IntPtr lParam) at System.Windows.Forms.NativeWindow.DefWndProc(Message& m) at System.Windows.Forms.Control.DefWndProc(Message& m) at System.Windows.Forms.Control.WmUpdateUIState(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.ScrollableControl.WndProc(Message& m) at System.Windows.Forms.ContainerControl.WndProc(Message& m) at System.Windows.Forms.ParkingWindow.WndProc(Message& m) at System.Windows.Forms.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

Please kindly help me to resolve this error.

Thanks and Regards, Jagadees.

Answer 1

The System.NullReferenceException exception is thrown when an null object reference is dereferenced.

In your application, you should make sure that you are not passing around Null values which should be set to valid data. The stack trace you provided is not enough to trace where the error occurs.