Did you find a solution to this? I'm getting:
11:57:19,156 INFO [Ejb3Configuration] found EJB3 Entity bean: com.ninem.rx.domain.site.Site
11:57:20,046 INFO [AnnotationBinder] Binding entity from annotated class: com.ninem.rx.domain.site.Site 11:57:20,046 INFO [EntityBinder] Bind entity com.ninem.rx.domain.site.Site on table site
11:57:20,359 INFO [CollectionBinder] Mapping collection: com.ninem.rx.domain.site.Site.users -> user
11:57:23,875 WARN [ServiceController] Problem starting service ninem:service=Admin javax.ejb.EJBException: java.lang.IllegalArgumentException: Unknown entity: com.ninem.rx.domain.site.Site
If it matters...I'm injecting my EntityManager via @Resource (It's in JNDI), and this exception occurs in the "start" method of a @Service Bean.
In my case, the error was due to a change in the build process. a "persistence.xml" file found its way into the JAR containing one of my services, and therefor this service was injecting the wrong persistence unit, leading to the errors above.
In our case, someone had deployed both the EAR and the JAR from inside the EAR.