The exception message issued by openjpa 2.0 for the use of an unenhanced class is not as useful as the message issued by the 1.x versions. In 2.0, the following message is received:
<openjpa-2.0.0-r422266:935683 nonfatal user error> org.apache.openjpa.persistence.ArgumentException: Attempt to cast instance "org.apache.sample.entities.Book@97781f" to PersistenceCapable failed. Ensure that it has been enhanced.
While the same application run using openjpa 1.x gives this message:
<openjpa-1.2.1-r752877:753278 fatal user error> org.apache.openjpa.persistence.ArgumentException: No metadata was found for type "class org.apache.sample.entities.Book". The class does not appear in the list of persistent types: [org.apache.geronimo.sample.entities.Book].
The 2.0 message no longer points to the persistence.xml definition as the potential source of error. It should give some possible solutions to "Ensure that is has been enhanced". Perhaps something like "Ensure that the class is included in the list of persistent types or enhanced as part of the application build".