Find out the details behind the “Unknown Error” screen.

Looking for more details on the "Unkown Error" screen, here is a great way to do it.
All you need to do is modify a couple things in web.config for the particular SharePoint site you are working on (granted it does require that you have Admin access to the SharePoint Server and folder).
  • In <SharePoint><SafeMode> set the CallStack property = "true"
  • In <system.web><compilation> set the debug property = "true"
  • In <system.web><customErrors> set the mode property = "Off"