I am using JPA under Hibernate for the first time. Contrary to native Hibernate, I find that error messages are not printed during booting (loading of configuration files...etc). I use the log4j logger with full display of messages from level TRACE on down, which should display all types of message. I get a huge list of trace and debug messages but because of some error in my setup, an exception is thrown. The frustrating thing is that the last error message is not displayed by my logger (log4j) so I don't really know what caused the exception that I need to fix. So I am left guessing about what's wrong, which is a huge expense of my time.

Is that normal? Is there a way to find out exactly what caused the exception?

Any help would be appreciated!

you might have something wrong in the logger configuration.
Any recent hibernate version (>=3.3.0) uses slf4j, did you add the implementation to provide the bridge to log4j ?
(slf4j is an adaptor, so that people can use the logging library they prefer - but you need to choose an implementation and drop it in your classpath)