Razor intellisense error: Feature 'extension method' cannot be used because it is not part of the ISO-2 C# language specification

Question

Goal:

• Use cshtml Razor templates to format data
• Embed cshtml Razor templates in Class Library as Embedded Resources

Answer 1

The solution for me was to change the project type

1.Unload the project

2.Edit project

3.Add line below (depending on your project MVC version) right after ProjectGuid

MVC 4

<ProjectTypeGuids>{E3E379DF-F4C6-4180-9B81-6769533ABE47};{349c5851-65df-11da-9384-00065b846f21};{fae04ec0-301f-11d3-bf4b-00c04f79efbc}</ProjectTypeGuids>

MVC 3

<ProjectTypeGuids>{E53F8FEA-EAE0-44A6-8774-FFD645390401};{349c5851-65df-11da-9384-00065b846f21};{fae04ec0-301f-11d3-bf4b-00c04f79efbc}</ProjectTypeGuids>

@Matt

Try adding this to the Web.Config in the Root of the project (not in the Views Folder)

<configuration>
...
 <configSections>
    <sectionGroup name="system.web.webPages.razor" type="System.Web.WebPages.Razor.Configuration.RazorWebSectionGroup, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35">
      <section name="host" type="System.Web.WebPages.Razor.Configuration.HostSection, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
      <section name="pages" type="System.Web.WebPages.Razor.Configuration.RazorPagesSection, System.Web.WebPages.Razor, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" requirePermission="false" />
    </sectionGroup>
  </configSections>
  <system.web.webPages.razor>
    <host factoryType="System.Web.Mvc.MvcWebRazorHostFactory, System.Web.Mvc, Version=3.0.0.0, 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>


...  
</configuration>

Answer 2

We had exactly this problem in our Project today - it could be replicated across team members so was not an install issue. Intellisense is compiling the pages to 2.0 code not CS# 3.

I tracked it down to adding a Web Reference to the Class Project (using MVCContrib to have it as a reference library as per http://lostechies.com/erichexter/2009/11/01/asp-net-mvc-portable-areas-via-mvccontrib/)

Took out the WebReference and moved it to another project and fixed the problem, took quite a bit of hunting so hope this helps someone else!

Answer 3

I tried all of the solutions to this error that I could find everywhere on the web and had no luck.

I finally got this error to disappear (and my IntelliSense to work) by copying the extra MVC configuration blocks from my project's web.config file to my project's app.config file.

Seems Visual Studio does not respect web.config (at least some of its parts) in a plain old C# library project.

My project's app.config file looks like this:

<appSettings>
    <add key="webpages:Version" value="2.0.0.0" />
    <add key="webpages:Enabled" value="false" />
    <add key="PreserveLoginUrl" value="true" />
    <add key="ClientValidationEnabled" value="true" />
    <add key="UnobtrusiveJavaScriptEnabled" value="true" />
  </appSettings>
  <system.web>
    <compilation debug="true" targetFramework="4.0">
      <assemblies>
        <add assembly="System.Web.Abstractions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Helpers, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Routing, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.Mvc, Version=3.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
        <add assembly="System.Web.WebPages, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
      </assemblies>
    </compilation>
    <pages>
      <namespaces>
        <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" />
      </namespaces>
    </pages>
  </system.web>
  <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>
      <dependentAssembly>
        <assemblyIdentity name="System.Web.WebPages" publicKeyToken="31bf3856ad364e35" culture="neutral" />
        <bindingRedirect oldVersion="0.0.0.0-2.0.0.0" newVersion="2.0.0.0" />
      </dependentAssembly>
    </assemblyBinding>
  </runtime>

Good luck.

Answer 4

After a couple hours more of tinkering, I found it had something to do with standard Visual Studio extensions not loading correctly.

I was receiving the error:

'VSTS for Database Professionals Sql Server Data-tier Application' package did not load correctly

I found the answer on on Microsoft Connect.

How to fix

1) Run the following installers from the Visual Studio media:

\WCU\DAC\DACFramework_enu.msi

\WCU\DAC\DACProjectSystemSetup_enu.msi

\WCU\DAC\TSqlLanguageService_enu.msi

2) Restart VS

Hope this can be of help to someone else.

Answer 5

The key of solving this issue is adding the following tag to your app.config or web.config

<system.web>
    <compilation debug="false" targetFramework="4.0" />
</system.web>

Note: In some cases, unloading and reloading the project is required.

Answer 6

Add a “system.codedom” section to your config file (app.config in a Console Application) eg:

<system.codedom>
<compilers>
<compiler language="c#;cs;csharp" extension=".cs;cshtml" type="Microsoft.CSharp.CSharpCodeProvider,System, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" warningLevel="4">
<providerOption name="CompilerVersion" value="v4.5"/>
<providerOption name="WarnAsError" value="false"/>
</compiler>
</compilers>
</system.codedom>