Comment 6 for bug 1016791

When you have a 500 bugs, you can get more info by using the symfony debug mode http://your_server/frontend_dev.php

Did your error come from creating the user? If so, it might be related to this one, the email configuration: https://bugs.launchpad.net/authpuppy/+bug/621394

Otherwise, reproduce the error in debug mode and post the detailed output.