Also I wonder if the problem really isn't simply a conceptual mismatch problem. You are asking Hibernate to treat the enum at the JDBC-level as a String (@Enumerated(STRING)). But in the database it isn't a String; its a UDT.

Let me finish this thought...

Also I wonder if the problem really isn't simply a conceptual mismatch problem. You are asking Hibernate to treat the enum at the JDBC-level as a String (@Enumerated(STRING)). But in the database it isn't a String; its a UDT. At this point either the driver properly handles the conversion, or it doesn't. The PostgreSQL driver does not, apparently not unless you specify this setting.

The documentation is undergoing a massive change for 5.1. That coupled with a still-unclear picture here means I am going to push this task to 5.1. I really would like for someone to play around with the NG driver before then.