在System.AddIn中托管WPF时出现NullReferenceException

Question

我们正在开发一个WPF应用程序，它使用System.AddIn框架来托管显示其他WPF内容的加载项。 一切似乎工作正常，但一夜之间，应用程序抛出了以下NullReferenceException：

Message: Error : Object reference not set to an instance of an object.
StackTrace :   at System.Windows.Interop.HwndSource.CriticalTranslateAccelerator(MSG& msg, ModifierKeys modifiers)
   at System.AddIn.Pipeline.AddInHwndSourceWrapper.TranslateAccelerator(MSG msg, ModifierKeys modifiers)
   at MS.Internal.Controls.AddInHost.System.Windows.Interop.IKeyboardInputSink.TranslateAccelerator(MSG& msg, ModifierKeys modifiers)
   at System.Windows.Interop.HwndHost.OnKeyUp(KeyEventArgs e)
   at System.Windows.UIElement.OnKeyUpThunk(Object sender, KeyEventArgs e)
   at System.Windows.Input.KeyEventArgs.InvokeEventHandler(Delegate genericHandler, Object genericTarget)
   at System.Windows.RoutedEventArgs.InvokeHandler(Delegate handler, Object target)
   at System.Windows.RoutedEventHandlerInfo.InvokeHandler(Object target, RoutedEventArgs routedEventArgs)
   at System.Windows.EventRoute.InvokeHandlersImpl(Object source, RoutedEventArgs args, Boolean reRaised)
   at System.Windows.UIElement.RaiseEventImpl(RoutedEventArgs args)
   at System.Windows.UIElement.RaiseEvent(RoutedEventArgs args, Boolean trusted)
   at System.Windows.Input.InputManager.ProcessStagingArea()
   at System.Windows.Input.InputManager.ProcessInput(InputEventArgs input)
   at System.Windows.Input.InputProviderSite.ReportInput(InputReport inputReport)
   at System.Windows.Interop.HwndKeyboardInputProvider.ReportInput(IntPtr hwnd, InputMode mode, Int32 timestamp, RawKeyboardActions actions, Int32 scanCode, Boolean isExtendedKey, Boolean isSystemKey, Int32 virtualKey)
   at System.Windows.Interop.HwndKeyboardInputProvider.ProcessKeyAction(MSG& msg, Boolean& handled)
   at System.Windows.Interop.HwndSource.CriticalTranslateAccelerator(MSG& msg, ModifierKeys modifiers)
   at System.Windows.Interop.HwndSource.OnPreprocessMessage(Object param)
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Boolean isSingleParameter)
   at System.Windows.Threading.ExceptionWrapper.TryCatchWhen(Object source, Delegate callback, Object args, Boolean isSingleParameter, Delegate catchHandler)
   at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Boolean isSingleParameter)
   at System.Windows.Threading.Dispatcher.Invoke(DispatcherPriority priority, Delegate method, Object arg)
   at System.Windows.Interop.HwndSource.OnPreprocessMessageThunk(MSG& msg, Boolean& handled)
   at System.Windows.Interop.HwndSource.WeakEventPreprocessMessage.OnPreprocessMessage(MSG& msg, Boolean& handled)
   at System.Windows.Interop.ThreadMessageEventHandler.Invoke(MSG& msg, Boolean& handled)
   at System.Windows.Interop.ComponentDispatcherThread.RaiseThreadMessage(MSG& msg)
   at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame)
   at System.Windows.Threading.Dispatcher.Run()
   at System.Windows.Application.RunInternal(Window window)
   at System.Windows.Application.Run(Window window)
   at System.Windows.Application.Run()

正如您所看到的，我们的代码都不在堆栈跟踪中，因此我没有任何地方可以解决任何问题。 有人对可能的解决方法有任何想法吗？

谢谢您的帮助！

Answer 1

我相信您需要关注的第一件事是更改Visual Studio中的设置。 我有很多问题，必须手动告诉Visual Studio打破NullReferenceException。 进行此调整后，IDE将实际抛出错误，您可以调试代码。 从VS 2008帮助：

在抛出异常时中断执行在“调试”菜单上，单击“例外”。

在“例外”对话框中，为整个例外类别选择“投掷”，例如“公共语言运行时例外”。

-要么-

展开一个例外类别的节点，例如，Common Language Runtime Exceptions，并为该类别中的特定异常选择Thrown。

Answer 2

此外，Steve Massing的上述答案可能有助于禁用“Just My Code”选项，启用“启用源服务器支持”选项并设置调试符号以便打入并调试框架代码，

它听起来比听起来容易，遵循这三个方向

红线未选中，绿线检查并设置如下符号

<sub>（来源： gangleri.net ）

（来源： gangleri.net ）</sub>