web.config

<?xml version="1.0"?>
<configuration>
  <configSections>
    <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor">
      <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor" requirePermission="false" />
      <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor" requirePermission="false" />
    </sectionGroup>
  </configSections>
  <system.web.webPages.razor>
    <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc"/>
    <pages pageBaseType="DotNetNuke.Web.Mvc.Framework.DnnWebViewPage">
      <namespaces>
        <add namespace="System.Linq"/>
        <add namespace="System.Web.Helpers" />
        <add namespace="System.Web.Mvc" />
        <add namespace="System.Web.Mvc.Ajax" />
        <add namespace="System.Web.Mvc.Html" />
        <add namespace="System.Web.Routing" />
        <add namespace="System.Web.WebPages" />
        <add namespace="DotNetNuke.Web.Mvc.Helpers"/>
      </namespaces>
    </pages>
  </system.web.webPages.razor>
</configuration>