The type 'System.Web.Mvc.ViewPage' is ambiguous

asp.net-mvc

Solution

I see that you have provided yourself an answer, but another solution is to update your web.config with a `<runtime>` element that redirects dependent assemblies and points to the correct one:

 <runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
      <dependentAssembly>
        <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>

Note that updating your project from NuGet does the same thing for you automatically for most assemblies.

Problem

Original source