为什么我在新项目页面中有“对象引用未设置为实例”

Question

我刚刚将我的Visual Studio从Silverlight 3更新为Silverlight 4，并开始出现这个不寻常的错误消息。

无论我创建了多少个项目，它都是一样的。重启Visual Studio和我的机器，仍然是同样的事情

更新：我已经从图像中复制了堆栈跟踪

System.NullReferenceException
Object reference not set to an instance of an object.
   at Microsoft.Windows.Design.Platform.SilverlightMetadataContext.SilverlightXamlExtensionImplementations.<GetXmlNamespaceCompatibilityMappings>d__8.MoveNext()
   at MS.Internal.Design.Metadata.ReflectionProjectNode.BuildSubsumption()
   at MS.Internal.Design.Metadata.ReflectionProjectNode.SubsumingNamespace(Identifier identifier)
   at MS.Internal.Design.Markup.XmlElement.BuildScope(PrefixScope parentScope, IParseContext context)
   at MS.Internal.Design.Markup.XmlElement.ConvertToXaml(XamlElement parent, PrefixScope parentScope, IParseContext context, IMarkupSourceProvider provider)
   at MS.Internal.Design.DocumentModel.DocumentTrees.Markup.XamlSourceDocument.FullParse(Boolean convertToXamlWithErrors)
   at MS.Internal.Design.DocumentModel.DocumentTrees.Markup.XamlSourceDocument.get_RootItem()
   at Microsoft.Windows.Design.DocumentModel.Trees.ModifiableDocumentTree.get_ModifiableRootItem()
   at Microsoft.Windows.Design.DocumentModel.MarkupDocumentManagerBase.get_LoadState()
   at MS.Internal.Host.PersistenceSubsystem.Load()
   at MS.Internal.Host.Designer.Load()
   at MS.Internal.Designer.VSDesigner.Load()
   at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedView.Load()
   at MS.Internal.Designer.VSIsolatedDesigner.VSIsolatedDesignerFactory.Load(IsolatedView view)
   at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view)
   at MS.Internal.Host.Isolation.IsolatedDesigner.BootstrapProxy.LoadDesigner(IsolatedDesignerFactory factory, IsolatedView view)
   at MS.Internal.Host.Isolation.IsolatedDesigner.Load()
   at MS.Internal.Designer.DesignerPane.LoadDesignerView()

Answer 1

我通过安装Silverlight 4运行时解决了这个问题。每当您在Visual Studio中单击建议的先决条件更新链接时，都会安装最新版本，该版本目前是Silverlight 5运行时，这不是我想要的。如果我们可以选择安装哪个选项而不是安装破坏内容的最新版本，那就没问题了。

我卸载了Silverlight 5运行时并使用这些链接来重新安装版本4

以下是我使用的链接：

• http://www.microsoft.com/en-us/download/details.aspx?id=18149
• http://www.microsoft.com/en-us/download/confirmation.aspx?id=18149

这个答案的建议

• Where can I get the "Silverlight Developer Runtime" for Silverlight 4?

Answer 2

引用旧版本时出现此错误，因此您应为您添加新参考更新版本