I have made that dreadful error of upgrading from MVC4 to MVC5 pre-release by updating the razor, and mvc webpage in my references I have System.Web.Mvc, System.Web.Webpages, System.Web.Webpages.Razor and System.Web.Razor as version v4.0.30319, when I run my application I get

[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=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'.

Type B originates from
'System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, 
PublicKeyToken=31bf3856ad364e35' in the context 'Default' at location 
'C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\membership\c70f06fe\9163b1ca\assembly\dl3\291c956e\73c25daa_cf74ce01\System.Web.WebPages.Razor.dll'.

is this the same as http://www.asp.net/whitepapers/mvc4-release-notes

Thanks

Adding a stacktrace:

[InvalidCastException: [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=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'. Type B originates from 'System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35' in the context 'Default' at location

'C:\Windows\Microsoft.NET\Framework64\v4.0.30319\Temporary ASP.NET Files\c70f06fe\9163b1ca\assembly\dl3\291c956e\73c25daa_cf74ce01\System.Web.WebPages.Razor.dll'.]
System.Web.WebPages.Razor.WebRazorHostFactory.CreateHostFromConfig(String virtualPath, String physicalPath) +193
System.Web.WebPages.Razor.RazorBuildProvider.GetHostFromConfig() +51
System.Web.WebPages.Razor.RazorBuildProvider.CreateHost() +24
System.Web.WebPages.Razor.RazorBuildProvider.get_Host() +34
System.Web.WebPages.Razor.RazorBuildProvider.EnsureGeneratedCode() +85
System.Web.WebPages.Razor.RazorBuildProvider.get_CodeCompilerType() +34
System.Web.Compilation.BuildProvider.GetCompilerTypeFromBuildProvider(BuildProvider buildProvider) +189
System.Web.Compilation.BuildProvidersCompiler.ProcessBuildProviders() +265
System.Web.Compilation.BuildProvidersCompiler.PerformBuild() +21
System.Web.Compilation.BuildManager.CompileWebFile(VirtualPath virtualPath) +580
System.Web.Compilation.BuildManager.GetVPathBuildResultInternal(VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +571
System.Web.Compilation.BuildManager.GetVPathBuildResultWithNoAssert(HttpContext context, VirtualPath virtualPath, Boolean noBuild, Boolean allowCrossApp, Boolean allowBuildInPrecompile, Boolean throwIfNotFound, Boolean ensureIsUpToDate) +203
System.Web.Compilation.BuildManager.GetVirtualPathObjectFactory(VirtualPath virtualPath, HttpContext context, Boolean allowCrossApp, Boolean throwIfNotFound) +249
System.Web.Compilation.BuildManager.GetCompiledType(VirtualPath virtualPath) +17
System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +90
System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +380
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +109
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +890
System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +97
System.Web.Mvc.Async.<>c__DisplayClass1e.<BeginInvokeAction>b__1b(IAsyncResult asyncResult) +241
System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +29
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +111
System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +53
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +19
System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__4(IAsyncResult asyncResult, ProcessRequestState innerState) +51
System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +111
System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +606
System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +288

Solution 1:

Found out what need to be done in Views\Web.config. Just copy & paste these sections over what you have:

<configSections>
    <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
        <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
        <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
    </sectionGroup>
</configSections>

<host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />

<pages
    validateRequest="false"
    pageParserFilterType="System.Web.Mvc.ViewTypeParserFilter, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
    pageBaseType="System.Web.Mvc.ViewPage, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35"
    userControlBaseType="System.Web.Mvc.ViewUserControl, System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
  <controls>
    <add assembly="System.Web.Mvc, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" namespace="System.Web.Mvc" tagPrefix="mvc" />
  </controls>
</pages>

And that was it. Job done! :D

Solution 2:

i suggest to see this from http://asp.net website

http://www.asp.net/mvc/tutorials/mvc-5/how-to-upgrade-an-aspnet-mvc-4-and-web-api-project-to-aspnet-mvc-5-and-web-api-2

Solution 3:

have you just updated the project references? Did you also check the web.config? There are also those libraries referenced and usually with specific version numbers of the library itself.

in the web.config you can find the referenced libraries for instance in:

<runtime>
    <assemblyBinding xmlns="urn:schemas-microsoft-com:asm.v1">
        <dependentAssembly>
            <assemblyIdentity name="System.Web.Helpers" publicKeyToken="31bf3856ad364e35" />
            <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
        </dependentAssembly>
        <dependentAssembly>
            <assemblyIdentity name="System.Web.Mvc" publicKeyToken="31bf3856ad364e35" />
            <bindingRedirect oldVersion="0.0.0.0-4.0.0.0" newVersion="4.0.0.0" />
        </dependentAssembly>
        <dependentAssembly>
            <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" />
            <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
        </dependentAssembly>
        <dependentAssembly>
            <assemblyIdentity name="System.Web.WebPages.Razor" publicKeyToken="31bf3856ad364e35" culture="neutral" />
            <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
        </dependentAssembly>
    </assemblyBinding>
</runtime>

or

<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>

or

<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>