Sonar does not officially support the JBoss AS7 application server / servlet container (or any JBoss version). By default, JBoss's JPA modules notice the
sonar-core-2.13.1.jar!/META-INF/persistence.xmland attempt to setup JPA (Hibernate). This fails (because Sonar isn't expecting JBoss to be doing anything in the way of setting up Hibernate). One solution is to remove the JPA module from JBoss.