title: Razor pages in MVC are giving a compile error with System.Web.Helpers not being found
body: <p>My razor view is failing to compile with the following error:</p>
  
  <pre><code>Description: An error occurred during the compilation of a resource required to service this request. Please review the following specific error details and modify your source code appropriately. 
  
  Compiler Error Message: CS0234: The type or namespace name 'Helpers' does not exist in the namespace 'System.Web' (are you missing an assembly reference?)
  </code></pre>
  
  <p>I have System.Web.Helpers added as a reference to my project, so I am not sure what else I need to do.  I have also tried a clean rebuild after adding the reference, and no change.  </p>
  
  <p>What am I missing?</p>