Security Misconfiguration.

To reduce the danger of hacking:

To setup error handling in a Java web app, add this to web.xml:

<error-page>
  <exception-type>java.lang.Throwable</exception-type>
  <location>/errorPage</location>
</error-page>

The action or controller that responds to the /errorPage request should log the exception, then forward to a simple web page that displays a timestamp and a link back to the home page. A simple message like "There has been an error. Please note down the time displayed on this page and call ....." is enough for the user.