Web Development with Clojure, Third Edition: "Internal Server Error" when trying to log in

Hi Dmitri Sotnikov @dmitri and Scot Brown @svmbrown,

I am trying to run some of the source code. Sometimes I’m able to log in fine (running guestbook-feeds-2 for example) and other times, I get “Internal Server Error” (for example, with guestbook-session). This happens with both “Log in” and “Register” where I get “Internal Server Error.” Is this something to do with Postgres? How do I debug this?

Thank you!