WPF 设计器无法加载

Question

在 Win7 上使用 Visual Studio 2012。

我最近将 WPF 应用程序转换为 WPF 用户控件，方法是将 XAML 标志 替换为 并将资源更改为 。为了安全起见，我还更改了从 UserControl 继承的代码隐藏，但在某些时候这破坏了应用程序，我无法再在设计模式下查看它。我得到的只是这些废话：

System.NullReferenceException
Object reference not set to an instance of an object.
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOutSynchronous(Action action, Int32 targetApartmentId, WaitHandle aborted, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOut(Action action, Int32 targetApartmentId, WaitHandle aborted, CallSynchronizationMode syncMode, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TValue](RemoteHandle`1 targetObject, Action action, CallSynchronizationMode syncMode)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TResult,TValue](RemoteHandle`1 targetObject, Func`2 func, CallSynchronizationMode syncMode)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CreateDesignerImpl(IHostSourceItem item, IHostTextEditor editor, RemoteCancellationToken remoteCancelToken)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.<>c__DisplayClass12.<Microsoft.Expression.DesignHost.IDesignerService.CreateDesigner>b__11(RemoteCancellationToken remoteToken)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.CallWithCancellation[TResult](CancellationToken cancelToken, Func`2 func)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.Microsoft.Expression.DesignHost.IDesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken)
   at Microsoft.Expression.DesignHost.IsolatedDesignerService.IsolatedDesignerView.CreateDesignerViewInfo(CancellationToken cancelToken)

System.NullReferenceException
Object reference not set to an instance of an object.

Server stack trace: 
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalIn(Action action, Int32 targetApartmentId)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn(IRemoteObject targetObject, Action action)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn[TResult](IRemoteObject targetObject, Func`1 func)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner(IRemoteHostSourceItem remoteItem, IRemoteHostTextEditor remoteEditor, IRemoteCancellationToken remoteToken)
   at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
   at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg)

Exception rethrown at [0]: 
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner(IRemoteHostSourceItem remoteItem, IRemoteHostTextEditor remoteEditor, IRemoteCancellationToken cancelToken)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalDesignerService.<>c__DisplayClass8.<CreateDesignerImpl>b__6(IRemoteDesignerService d)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass4`2.<MarshalOut>b__3()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()

System.NullReferenceException
Object reference not set to an instance of an object.
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOutSynchronous(Action action, Int32 targetApartmentId, WaitHandle aborted, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalOut(Action action, Int32 targetApartmentId, WaitHandle aborted, CallSynchronizationMode syncMode, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TValue](RemoteHandle`1 targetObject, Action action, CallSynchronizationMode syncMode)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalOut[TResult,TValue](RemoteHandle`1 targetObject, Func`2 func, CallSynchronizationMode syncMode)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalHostProjectService.Microsoft.Expression.DesignHost.IHostProjectService.FindProject(FindProjectCriteria criteria, String criteriaValue)
   at Microsoft.Expression.DesignSurface.Project.ProjectContextManager.FindApplicationProjectContext(XamlProjectContext requestingContext)
   at Microsoft.Expression.DesignSurface.Project.XamlProjectContext.get_Application()
   at Microsoft.Expression.DesignSurface.Documents.SceneDocument.GetApplicationDocument(IXamlProjectContext activeContext)
   at Microsoft.Expression.DesignSurface.Documents.SceneDocument.get_ApplicationSceneDocument()
   at Microsoft.Expression.DesignSurface.DocumentViewContext.CreateAndOpenView(ISourceItemContext sourceItem, CancellationToken cancelToken, Boolean activate, Boolean ensureOpenInHost, Boolean suppressUI)
   at Microsoft.Expression.DesignSurface.DesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.<>c__DisplayClass10.<>c__DisplayClass12.<Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner>b__f(CancellationToken cancelToken)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.CallWithCancellation[TResult](IRemoteCancellationToken remoteToken, Func`2 func)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteDesignerService.<>c__DisplayClass10.<Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteDesignerService.CreateDesigner>b__e()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass16`1.<MarshalIn>b__15()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()

System.NullReferenceException
Object reference not set to an instance of an object.

Server stack trace: 
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalIn(Action action, Int32 targetApartmentId)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn(IRemoteObject targetObject, Action action)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn[TResult](IRemoteObject targetObject, Func`1 func)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteHostProjectService.Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteHostProjectService.FindProject(FindProjectCriteria criteria, String criteriaValue)
   at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
   at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg)

Exception rethrown at [0]: 
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteHostProjectService.FindProject(FindProjectCriteria criteria, String criteriaValue)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.LocalHostProjectService.<>c__DisplayClass7.<Microsoft.Expression.DesignHost.IHostProjectService.FindProject>b__6(IRemoteHostProjectService ps)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass4`2.<MarshalOut>b__3()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()

System.NullReferenceException
Object reference not set to an instance of an object.
   at MS.Internal.VSUtilities.GetBuildAction(IVsHierarchy hierarchy, UInt32 itemid)
   at Microsoft.VisualStudio.ExpressionHost.HostServices.HostSourceItem.<>c__DisplayClass9.<Microsoft.Expression.DesignHost.IHostSourceItem.get_BuildItemType>b__7()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.Invoke(Boolean waitingInExternalCall)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.InvokeCall(Call call)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.DirectInvoke(Action action, Int32 sourceApartmentId, Int32 targetApartmentId, Int32 originId, WaitHandle aborted)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.DirectInvokeInbound(Action action, Int32 targetApartmentId)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.MarshalIn(Action action, Int32 targetApartmentId)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.MarshalIn(IRemoteObject targetObject, Action action)
   at Microsoft.VisualStudio.ExpressionHost.HostServices.HostSourceItem.Microsoft.Expression.DesignHost.IHostSourceItem.get_BuildItemType()
   at Microsoft.Expression.HostUtility.Extensions.HostExtensions.<HasApplicationDocument>b__0(IHostSourceItem i)
   at System.Linq.Enumerable.Any[TSource](IEnumerable`1 source, Func`2 predicate)
   at Microsoft.Expression.HostUtility.Extensions.HostExtensions.HasApplicationDocument(IHostProject hostProject)
   at Microsoft.VisualStudio.ExpressionHost.HostServices.HostProjectService.FindApplicationProject(String projectPath)
   at Microsoft.VisualStudio.ExpressionHost.HostServices.HostProjectService.<FindProjectsInternal>d__30.MoveNext()
   at System.Linq.Enumerable.FirstOrDefault[TSource](IEnumerable`1 source)
   at Microsoft.VisualStudio.ExpressionHost.HostServices.HostProjectService.Microsoft.Expression.DesignHost.IHostProjectService.FindProject(FindProjectCriteria criteria, String criteriaValue)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteHostProjectService.<>c__DisplayClass1d.<Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteHostProjectService.FindProject>b__1c()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass16`1.<MarshalIn>b__15()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()

经过几次谷歌搜索后，我发现这是 2012 年的一个热门问题，但从那以后似乎几乎消失了。但现在我无事可做！我所有的程序集都是 3.5+（当时 2.0 程序集是一个已知问题），我尝试删除引用，但这也无济于事。除了在控件的负载中实例化 IoC 之外，我几乎没有进行任何代码更改，但我也完全删除了该代码，但无济于事。

有没有人遇到过这个问题？

编辑 - 请注意，如果我添加一个完全没有自定义的新 UserControl 并尝试查看它，我会得到同样的错误。

编辑 2 - 尝试“附加到进程”，当我尝试重新加载设计器时它没有做任何事情。

Answer 1

这是 Visual Studio 在创建不正确的中间文件时的错误。仅重建所有项目可能无法解决问题。

试试这个，

1. 关闭 Visual Studio。
2. 删除“obj”文件夹。
3. 重新打开 Visual Studio。
4. 重建所有项目。

祝你好运！

Answer 2

其中一个原因可能是您的某些静态资源绑定到临时为空的对象

它可能是例如绑定到 RowData.Row.Property，其中行是另一个资源的当前行，在设计时为空。

更好的方法是使用 Converter 绑定到 RowData.Row

public object Convert(object value, Type targetType, object parameter,
                  System.Globalization.CultureInfo culture)        
{
    if (value is MyContentType)
    {
      return (value as MyContentType).Property
    }
    else
    { 
       return defaultValue // this value is valid for wpf control property
    }

}         

其他原因可能是您的某些转换器或模板选择器没有检查传入值是否为空

可能是别的东西，但我不知道....

Answer 3

在注意到我的其他同事可以很好地看到控件后，终于弄明白了。

在这种情况下，答案似乎是我的 Visual Studio 仍处于第一个版本，需要更新到版本 4。因此，如果所有其他方法都失败并且其他人遇到此问题，请下载最新的 Visual Studio 补丁并启动它关了。我敢肯定，当它安装完成后，它会再次工作。