Upgrading an ASP.NET MVC 3 Project to ASP.NET MVC 4 - asp.net

Question

I have an asp.net MVC3 project I made an upgrade to asp.net mvc4 following this tutorial:
http://www.asp.net/whitepapers/mvc4-release-notes#_Toc303253806
I get the following error when I execute the project
[A]System.Web.WebPages.Razor.Configuration.HostSection cannot be cast
to [B]System.Web.WebPages.Razor.Configuration.HostSection. Type A
originates from 'System.Web.WebPages.Razor, Version=1.0.0.0,
Culture=neutral, PublicKeyToken=31bf3856ad364e35' in the context
'Default' at location
'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.WebPages.Razor\v4.0_1.0.0.0__31bf3856ad364e35\System.Web.WebPages.Razor.dll'.
Type B originates from 'System.Web.WebPages.Razor, Version=2.0.0.0,
Culture=neutral, PublicKeyToken=31bf3856ad364e35' in the context
'Default' at location
'C:\Windows\Microsoft.Net\assembly\GAC_MSIL\System.Web.WebPages.Razor\v4.0_2.0.0.0__31bf3856ad364e35\System.Web.WebPages.Razor.dll'.

Answer 1

Step by step instructions can be found here:
http://www.asp.net/whitepapers/mvc4-release-notes#_Toc303253806
Specifically you're interested in binding redirects in your web.config.
<dependentAssembly>
<assemblyIdentity name="System.Web.WebPages"
publicKeyToken="31bf3856ad364e35" />
<bindingRedirect oldVersion="1.0.0.0" newVersion="2.0.0.0"/>
</dependentAssembly>
and don't forget to add the following to your <appSettings>
<add key="webpages:Version" value="2.0.0.0" />

Answer 2

Please change your webconfig in Views folder to below code if you upgrade to mvc4 from mvc3
<configuration>
<configSections>
<sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
<section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
<section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=2.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
</sectionGroup>
</configSections>
<system.web.webPages.razor>
<host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
<pages pageBaseType="System.Web.Mvc.WebViewPage">
<namespaces>
<add namespace="System.Web.Mvc" />
<add namespace="System.Web.Mvc.Ajax" />
<add namespace="System.Web.Mvc.Html" />
<add namespace="System.Web.Routing" />
</namespaces>
</pages>
</system.web.webPages.razor>
<pages
validateRequest="false"
pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
<controls>
<add assembly="System.Web.Mvc, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.Mvc" tagPrefix="mvc" />
</controls>
</pages>
</system.web>