在项目创建后在XAML设计器抛出NullReference

本文关键字：NullReference 项目 创建 XAML | 更新日期: 2023-09-27 18:11:07

我得到了这个异常抛出后，我试图打开XAML文件在UWP项目

System.NullReferenceException
Object reference not set to an instance of an object.
   at Microsoft.VisualStudio.DesignTools.Platform.Metadata.MetadataStore.GetTypeConverter(Type type)
   at Microsoft.VisualStudio.DesignTools.WindowsXamlDesigner.WindowsUIXamlDesignTimeProperties.ResolveImplementation(IPlatformMetadata platformMetadata, DesignTimePropertyId neutralProperty, IType declaringType, PropertyChangedCallback callback)
   at Microsoft.VisualStudio.DesignTools.WindowsXamlDesigner.WindowsUIXamlDesignTimeProperties.RegisterProperty(IPropertyId neutralPropertyKey, IType declaringType, PropertyChangedCallback callback)
   at Microsoft.VisualStudio.DesignTools.WindowsXamlDesigner.WindowsUIXamlCommonDesignTimeProperties.Initialize(WindowsUIXamlDesignTimeProperties designTimeProperties)
   at Microsoft.VisualStudio.DesignTools.WindowsXamlDesigner.WindowsUIXamlDesignTimeProperties..ctor(IPlatformTypes platformMetadata)
   at Microsoft.VisualStudio.DesignTools.UniversalXamlDesigner.UniversalXamlPlatformMetadata.CreateDesignTimeProperties()
   at Microsoft.VisualStudio.DesignTools.WindowsXamlDesigner.Metadata.WindowsUIXamlPlatformMetadata.Initialize()
   at Microsoft.VisualStudio.DesignTools.WindowsXamlDesigner.WindowsStoreXamlPlatform.Initialize()
   at Microsoft.VisualStudio.DesignTools.Platform.PlatformCreatorBase.CreatePlatform(IPlatformReferenceAssemblyResolver referenceAssemblyResolver)
   at Microsoft.VisualStudio.DesignTools.Designer.Project.ProjectContextManager.GetProjectContext(IHostProject project, IPlatform platform, Boolean create)
   at Microsoft.VisualStudio.DesignTools.Designer.Project.ProjectContextManager.GetSourceItemContext(IHostSourceItem sourceItem)
   at Microsoft.VisualStudio.DesignTools.Designer.DesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.RemoteDesignerService.<>c__DisplayClass12_0.<Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.IRemoteDesignerService.CreateDesigner>b__0(CancellationToken cancelToken)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.RemoteDesignerService.<>c__DisplayClass6_0`1.<MarshalInWithCancellation>b__0()
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()
System.NullReferenceException
Object reference not set to an instance of an object.
Server stack trace: 
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.STAMarshaler.MarshalInSynchronous(Action action, Int32 targetApartmentId, CancellationToken cancelToken, CallModality callModality, String methodName, String filePath, Int32 lineNumber)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.STAMarshaler.MarshalIn(Action action, Int32 targetApartmentId, CancellationToken cancelToken, CallSynchronizationMode syncMode, CallModality callModality, String methodName, String filePath, Int32 lineNumber)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.ThreadMarshaler.MarshalIn(IRemoteObject targetObject, Action action, CancellationToken cancelToken, CallSynchronizationMode syncMode, CallModality callModality, ApartmentState apartmentState, String memberName, String filePath, Int32 lineNumber)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.RemoteDesignerService.MarshalInWithCancellation[TResult](IRemoteCancellationToken remoteToken, Func`2 func, ApartmentState apartmentState)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.RemoteDesignerService.Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.IRemoteDesignerService.CreateDesigner(IRemoteHostProject remoteProject, 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.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.IRemoteDesignerService.CreateDesigner(IRemoteHostProject remoteProject, IRemoteHostSourceItem remoteItem, IRemoteHostTextEditor remoteEditor, IRemoteCancellationToken cancelToken)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.LocalDesignerService.CreateDesignerImpl(IRemoteDesignerService ds, IHostSourceItem item, IHostTextEditor editor, RemoteCancellationToken remoteCancelToken)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.LocalDesignerService.<>c__DisplayClass14_0.<Microsoft.VisualStudio.DesignTools.DesignerContract.IDesignerService.CreateDesigner>b__0(IRemoteDesignerService ds, RemoteCancellationToken remoteToken)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.LocalDesignerService.<>c__DisplayClass5_0`1.<MarshalOutWithCancellation>b__0(IRemoteDesignerService ds)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass27_0`1.<MarshalOut>b__0()
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()
System.NullReferenceException
Object reference not set to an instance of an object.
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.STAMarshaler.WaitForCompletion(NestedCallContext nestedCallContext, BlockingCall call, WaitHandle timeoutSignal)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.STAMarshaler.MarshalOutSynchronous(Action action, Int32 targetApartmentId, WaitHandle aborted, WaitHandle timeoutSignal, CancellationToken cancelToken, String methodName, String filePath, Int32 lineNumber)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.STAMarshaler.MarshalOut(Action action, Int32 targetApartmentId, WaitHandle aborted, CancellationToken cancelToken, CallSynchronizationMode syncMode, WaitHandle timeoutSignal, String methodName, String filePath, Int32 lineNumber)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.ThreadMarshaler.MarshalOut[TValue](RemoteHandle`1 targetObject, Action action, CancellationToken cancelToken, CallSynchronizationMode syncMode, ApartmentState apartmentState, String methodName, String filePath, Int32 lineNumber)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.ThreadMarshaler.MarshalOut[TValue](RemoteHandle`1 targetObject, Action`1 action, CancellationToken cancelToken, CallSynchronizationMode syncMode, ApartmentState apartmentState, String methodName, String filePath, Int32 lineNumber)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.LocalDesignerService.MarshalOutWithCancellation[TResult](CancellationToken cancelToken, Func`3 func, ApartmentState apartmentState)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.Isolation.Remoting.LocalDesignerService.Microsoft.VisualStudio.DesignTools.DesignerContract.IDesignerService.CreateDesigner(IHostSourceItem item, IHostTextEditor editor, CancellationToken cancelToken)
   at Microsoft.VisualStudio.DesignTools.DesignerContract.IsolatedDesignerService.IsolatedDesignerView.CreateDesignerViewInfo(CancellationToken cancelToken)

我没有做任何事情，而且这个Visual Studio是在我从8.1升级到10之后才安装的。在这个Visual Studio 2015之前，我曾经有过VS2013，我在升级到VS2015后立即卸载了它

我找到了一个关于它的帖子:https://social.msdn.microsoft.com/Forums/en-US/59ee2840-4329-413a-80ce-5c6a2f1390cc/rtm-known-issue-opening-a-xaml-page-from-a-c-uwp-in-visual-studio-2015-may-cause-the-xaml?forum=Win10SDKToolsIssues

但是这没有用

我的XAML发生了什么?

在项目创建后在XAML设计器抛出NullReference

这对我在两个不同的HP产品上都有效(HP设置了"Platform"环境变量)。

删除"System->Advanced System Settings-> environment Variables…"中的"Platform"环境变量

这里是=HPD

要解决此问题，请尝试以下步骤:

1)。关闭Visual Studio中现有的c++ UWP项目。

2)。在Visual Studio中创建一个虚拟c# UWP(文件->新建->项目->安装->模板-> Visual c# -> Windows ->通用->空白应用程序)

3)。打开主页。Xaml文件(双击它)。

4)。观察MainPage。Xaml文件打开正常

5)。如果MainPage。xaml页面打开良好，关闭您刚刚创建的虚拟项目并打开您遇到问题的c++项目。主页。Xaml页面现在应该正确地呈现，没有上述异常。

问题细节:

问题的发生是因为当XAML设计器正在加载时，它正在寻找"%userprofile%"中的内容。nuget"文件夹中。当您创建一个空白的c++ UWP时，.nuget文件夹在默认情况下不存在。一旦你创建了一个空白的c# UWP， .nuget包缓存就会被创建，然后XAML设计器就可以很好地工作，即使是在c++项目中。

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