NullReferenceException in Design Mode

[Kunal Chowdhury]

Every time I click on the RadListPicker (binary version: 2013.1.418.2040) tag when the designer window is open, it throws a NullReferenceException. If I click outside the tag the designer window comes back with the UI. Some time it needs a rebuild but again when I click the RadListPicker tag, it throws the same exception.

Here is my code:

<telerikInput:RadListPicker>
         <system:String>Demo 1</system:String>
         <system:String>Demo 2</system:String>
</telerikInput:RadListPicker>

Here is the exception details:

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

Stack Trace:

   at Microsoft.Expression.HostUtility.UriResolver.ComponentUriResolver.Parse(Uri uri, Uri baseUri, String assemblyName, IHostProject project)
   at Microsoft.Expression.HostUtility.UriResolver.ComponentUriResolver.TryResolve(Uri uri, String rootPath, String documentPath, String assemblyName, HostDesignTimeUriInfo& uriResolutionInfo)
   at Microsoft.Expression.HostUtility.UriResolver.UriResolverFactory.TryResolve(Uri uri, String rootPath, String referencingDocumentPath, String assemblyName, HostDesignTimeUriInfo& uriResolutionInfo)
   at Microsoft.Expression.HostUtility.UriResolver.UriResolver.TryResolve(Uri uri, String rootPath, String referencingDocumentPath, String assemblyName)
   at Microsoft.VisualStudio.ExpressionHost.HostServices.HostProjectService.Microsoft.Expression.DesignHost.IHostProjectService.MakeThemeResourceDesignTimeUri(Uri uri, String rootPath, String referencingDocumentPath, String assemblyName)
   at Microsoft.Expression.DesignHost.Isolation.Remoting.RemoteHostProjectService.<>c__DisplayClass32.<Microsoft.Expression.DesignHost.Isolation.Remoting.IRemoteHostProjectService.MakeThemeResourceDesignTimeUri>b__31()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.ThreadMarshaler.<>c__DisplayClass16`1.<MarshalIn>b__15()
   at Microsoft.Expression.DesignHost.Isolation.Remoting.STAMarshaler.Call.InvokeWorker()

What is wrong here? Is it a known issue or a bug? I am using the SP1 version of Q1.2013, I guess.

Thanks & Regards,
Kunal Chowdhury, Microsoft MVP | Telerik MVP

[Deyan]

Hi Kunal,

Can you please make sure that you have Update 2 for Visual Studio 2012 installed? If not, can you please install it and let us know if this issue is resolved?

Thanks for your time.

Regards,
Deyan
Telerik

[Kunal Chowdhury]

Hi Deyan,
    Yes, I am using the latest Visual Studio 2012 i.e. Update 2. Let me know, if I need to check anything else.
Regards,
Kunal

[Deyan]

Hello Kunal,

Thanks for writing back and please excuse me for the delay with my answer.

This issue is caused by a problem within Visual Studio 2012's designer which Microsoft were informed of and announced they will be fixing within Update 2. Interestingly though it persists when using Windows Phone 7.1. assemblies.

The issue was related to using MergedDictionaries within controls' styles in our assemblies.

I am going to revisit the case and I will get back to you by the end of the day with more details.

Thanks for your patience.

Regards,
Deyan
Telerik

[Kunal Chowdhury]

Thanks Dayan. Waiting for further details from your site.

[Robby Gunawan]

I have the same problem, please fix the error..

thanks

[Deyan]

Hi Robby,

We are working on this right now.

Regards,
Deyan
Telerik

[OTMOP]

Hello.

When this issue will be fixed? Is it fixed in the last internal build?

VS2012, Update 3.

Alexander.

[Kiril Stanoev]

Hello Alexander,

We haven't yet gotten the chance to fix this issue for WP 7. Everything seems to be working properly with WP8.

Regards,
Kiril Stanoev
Telerik

[Tony]

I am using VS2013 Update 1 with the latest Telerik Windows Phone 8 version and getting the same problem.  Obviously this hasn't been fixed?
​
   

[Deyan]

Hi Tony,

We will investigate and get back to you shortly.

Regards,
Deyan
Telerik

[Hugo Vladimir]

I solved the problem by upgrading telerik from visual studio, I had the same problem for a while but apparently already solved.