Always see NullReference exception in designer with all silverlight business applications in visual studio 2010

nullreferenceexceptionsilverlightvisual studio 2010

Starting with the most simple case.

If I press "File->new project->silverlight business application" it opens up to MainPage.xaml saying the message attached at the bottom of this post.

It also does the same thing to any silverlight business application that exists in sourcesafe – this is the first time I've personally needed to work on this technology.

Any advice would be very much appreciated I really need to get started on a project and I feel quite disabled to not have the designer.

Thanks in advance.

An Unhandled Exception has occured

Click here to reload the designer

Details:

System.NullReferenceException Object reference not set to an instance
of an object. at
Microsoft.Windows.Design.Platform.SilverlightMetadataContext.SilverlightXamlExtensionImplementations.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()

Best Answer

If you run into this issue, a possible cause is due to you having Microsoft SilverLight version 5.0 installed on your pc versus that of 4.0 (Version: 4.0.50826.0). Remove the copy of SilverLight 5.0. Install the version located at the following link - http://go.microsoft.com/fwlink/?LinkId=146060 DO NOT INSTALL version 5.0 IF YOU HAVE SDK 3 AND 4. INSTALL MICROSOFT SILVERLIGHT 4.0

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