Can't access /elmah on production server with Elmah MVC?

You need to enable Elmah for remote access by adding the following configuration setting to the <elmah> section in your web.config file. The default setting for this value is false, which only allows localhost, hence why it is working on your local machine from within Visual Studio.

   <elmah>
      <security allowRemoteAccess="true"/>
   </elmah>

I always seem to forget this myself and spend a few minutes scratching my head ;)

Make sure you HttpHandler is defined in the webServer section in your web.config file.

<system.webServer>
  <httpHandlers>
    <add name="elmah" verb="GET" path="elmah.axd"  type="Elmah.ErrorLogPageFactory, Elmah"/>
  </httpHandlers>
</system.webServer>