Здравствуйте, Funny Rabbit, Вы писали:

FR>приводит к такой ошибке

org.postgresql.util.PSQLException: Something unusual has occurred to cause the driver to fail. Please report this exception.

https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/Driver.java#L322
https://github.com/pgjdbc/pgjdbc/blob/master/pgjdbc/src/main/java/org/postgresql/Driver.java#L404

Установите setLevel(Level.FINE)