Hm, good question. I'd say WARN, or INFO even

This method is part of the standard JPA bootstrap process, within which not being able to build the EMF is nothing more than an INFO really. The idea being that there might be multiple PersistenceProvider instances available to process handle the PU. One of them encountering an error while trying to build the EMF is not an error condition to the JPA APis - we are just supposed to return null and JPA will go on to the next provider.