title: IIS Error : Service cannot be activated due to an exception during compilation. What is it?
body: <blockquote>
    <p>WebHost failed to process a request.</p>
    
    <p>Sender Information:  System.ServiceModel.ServiceHostingEnvironment+HostingManager/14938877
    Exception: System.ServiceModel.ServiceActivationException: The service '/xxxx.svc' cannot be activated due to an <strong>exception during compilation.</strong> </p>
  </blockquote>
  
  <p>I have an ASP.NET app running on IIS. A dev created operation contract with same name as we had already. Fine in VS. However it fails when deployed on the prod IIS.</p>
  
  <p>My question - what it has to do with compilation? Is there a conscious simple explanation whats happening in IIS with the app (in terms of post-deployment and hosting ASP.NET att)? What does it compile? What for?</p>