When I compile, I get the error "The type or namespace name 'Forms' does not exist in the namespace 'Umbraco' (are you missing an assembly reference?)". The offending line of code is (I am trying a code first approach to creating Contour forms):

public class SubscribeToNewsletter : Umbraco.Forms.CodeFirst.FormBase { }

Yes, I have a reference to Umbraco.Forms.CodeFirst, Umbraco.Forms.Core, and Umbraco.Core.Providers. And Visual Studio intellisense showed me that the class "FormBase" is in the namespace "CodeFirst".

The problem seems to be related to the fact that, even though I have referenced the Contour assemblies, the references cannot be resolved, as indicated by this compile warning:

The primary reference "Umbraco.Forms.CodeFirst, Version=3.0.15.0, Culture=neutral, processorArchitecture=MSIL" could not be resolved because it has an indirect dependency on the framework assembly "System.Web.Extensions, Version=1.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" which could not be resolved in the currently targeted framework. ".NETFramework,Version=v4.5". To resolve this problem, either remove the reference "Umbraco.Forms.CodeFirst, Version=3.0.15.0, Culture=neutral, processorArchitecture=MSIL" or retarget your application to a framework version which contains "System.Web.Extensions, Version=1.1.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35".

There are a total of 6 warnings, each of which look very similar to this one. I added emphasis above to point out what the main problem seems to be (i.e., something is referencing System.Web.Extensions 1.1.0.0). Note that I have binding redirects in my web.config for the old versions of this and the related assemblies:

<dependentAssembly>
 <assemblyIdentity name="System.Web.Extensions" publicKeyToken="31bf3856ad364e35" />
  <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="4.0.0.0" />
</dependentAssembly>
<dependentAssembly>
  <assemblyIdentity name="System.Web.Extensions.Design" publicKeyToken="31bf3856ad364e35" />
  <bindingRedirect oldVersion="1.0.0.0-1.1.0.0" newVersion="4.0.0.0" />
</dependentAssembly>

I tried to use dotPeek to find out where the assembly reference was coming from, but dotPeek seems to have a bug that made inspecting the reference hierarchy impossible (infinite hang). I also set MSBuild project build output verbosity to detailed, and it didn't provide any useful information.

I am using Umbraco 6.1.3 in an MVC4 project targeted against the .Net Framework 4.5. I installed Contour 3.0.14.0 from the repository in Umbraco, then noticed a new version, so I downloaded the upgrade package for Contour 3.0.15.0 and updated the DLL's in my project (note that I have experienced the same error/warnings before and after this Contour upgrade).

Any ideas to help troubleshoot this would be much appreciated.