How do I see the full error in a page which returns 500 internal error?
All I see is the error number and description -internal server error- with no exact details of the details of the error?
There are several ways to achieve this, though I would recommend setting up ELMAH.
It will log the exception with stack trace and provide a web interface to see it.
There are other loggers (log4net) and you can write your own logging (Exception.ToString() will provide most of the needed information for tracking down a bug), but I find ELMAH to be easy to get going.