title: The type or namespace name 'Mvc' does not exist in the namespace 'System.Web' (are you missing an assembly reference?)
body: <p>Whenever I try to compile my VS2015 application, I a long list of errors like:</p>
  
  <pre><code>The type or namespace name 'Mvc' does not exist in the namespace 'System.Web' (are you missing an assembly reference?)
  </code></pre>
  
  <p>However, as soon as I double click the error to view the file, it opens the file, has a slight delay, then clears ALL the errors. </p>
  
  <p>If I proceed to try and build again, I get the same list of errors and the process repeats itself.</p>
  
  <p><strong>UPDATE</strong>
  I forgot to mention that I have tried:</p>
  
  <ol>
  <li>following the advice in several other SO questions - to no avail</li>
  <li>ensuring the dlls are set to copy to local</li>
  <li>removing and re-adding references</li>
  <li>deleting dlls from the application and adding them back</li>
  <li>cleaning and rebuilding the application</li>
  <li>restarting the application and my computer</li>
  </ol>
  
  <p>What would cause this? How do I eliminate it?</p>