Problem:

Newly published a MVC web site, got a error message when trying to visit a page:

Compiler Error Message: CS0103: The name 'ViewBag' does not exist in the current context

Analyze:

The MVC sdk has already been installed on the host machine. By looking into the ViewBag’s definition, found it resides in the System.Web.Mvc.dll. So I copied this dll to the web folder’s ~\bin folder, but the error message is still there. And then I double checked the cshtml file and the error message, it was saying the ‘ViewBag’ does not exist in the current context, so I must lost the relative referencing statements. But adding these referencing statements in all the cshtml files is quite annoying, there must be a central place for adding these statements once and will take effects on all the cshtml files.

Solution:

By double checking the web.config, I found I’ve deleted some nodes that related these referencing statements some days earlier for fixing another issue. So I pasted these lost statements and then revisit the page, and then the error was gone!

If you removed these Razor related settings by purpose not to break some sub-applications, then you can paste these Razor related settings to the web.config under the ~/Views folder.

<?xml version="1.0"?>
<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>
	<!-- ViewBag is in this namespace! -->
        <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>