Coding days: System.NullReferenceException in Silverlight application designer in Visual Studio 2010

Friday 19 April 2013

System.NullReferenceException in Silverlight application designer in Visual Studio 2010

This is my Environment:

Windows 7 64 bit
VisualStudio 2010 with SilverLight 4 developer runtime

Problem: After upgrading the SilverLight 5 client, I tried to create a SilverLight Application and then I have got the following wired error message on the design tab

The text format of the error is:

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()

Solution: The problem is the conflict of SilverLight versions and I have found the solution in this thread.

Step 1: Uninstall the latest SilverLight client which is SilverLight 5, the 1st one in the below control panel screen shot

Step 2: Uninstall SilverLight 4 developer, the next 1 in the above image

Step 3: Download and Install Microsoft Silverlight 4 Tools for Visual Studio 2010 (Add-on and pre-requisite files for Visual Studio 2010 to develop Silverlight 4 and RIA Services applications)