Question

I am currently trying to make an existing VB.NET Project run. A null pointer exception is thrown in the WndProc message but the stack trace does not really give me anything. I can place a break point in the startup form’s designer code but when I step through it triggers a NULL pointer exception via WndProc function. The upper methods seems to be Windows methods. The only clue I have is the Message parameter with Msg = 24 and WParam = 1. I think the HWnd = 5178884 does not help.

I am pasting the stack trace in case someone has any ideas.
Note: I masked the MyNamespace and MyBaseForm and MyFormA because the source code is proprietary. This runs in Visual Studio 2008 on .NET Framework 3.5

MyNamespace.Forms.MyBaseForm.WndProc(Message& m)\r\n   
System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)\r\n   
System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)\r\n   
System.Windows.Forms.NativeWindow.DebuggableCallback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)\r\n   
System.Windows.Forms.SafeNativeMethods.ShowWindow(HandleRef hWnd, Int32 nCmdShow)\r\n   
System.Windows.Forms.Control.SetVisibleCore(Boolean value)\r\n   
System.Windows.Forms.Form.SetVisibleCore(Boolean value)\r\n   
System.Windows.Forms.Control.set_Visible(Boolean value)\r\n   
System.Windows.Forms.Application.ThreadContext.RunMessageLoopInner(Int32 reason, ApplicationContext context)\r\n   
System.Windows.Forms.Application.ThreadContext.RunMessageLoop(Int32 reason, ApplicationContext context)\r\n   
System.Windows.Forms.Application.Run(ApplicationContext context)\r\n   
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.OnRun()\r\n   
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.DoApplicationModel()\r\n   
Microsoft.VisualBasic.ApplicationServices.WindowsFormsApplicationBase.Run(String[] commandLine)\r\n   
MyFormA.My.MyApplication.Main(String[] Args) 
17d14f5c-a337-4978-8281-53493378c1071.vb:Line 81\r\n   
System.AppDomain._nExecuteAssembly(Assembly assembly, String[] args)\r\n   
System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)\r\n   
Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()\r\n   
System.Threading.ThreadHelper.ThreadStart_Context(Object state)\r\n   
System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)\r\n   
System.Threading.ThreadHelper.ThreadStart()"

Answer 1

WM_SHOWWINDOW = 24

…not that it really helps.
It looks like the last bit of your code to be executed is line 81, I’d study that.