In my persistence.xml the following properties caused the problem:
<property name="hibernate.transaction.manager_lookup_class" value="org.hibernate.transaction.JBossTransactionManagerLookup"/> <property name="hibernate.transaction.factory_class" value="org.hibernate.transaction.JTATransactionFactory"/>
After removing the lines, it worked.
Not sure if you found more information, but here is what I have discovered through testing...
I experienced the same problem with the transaction configuration. Seems that when you configure Hibernate with a factory_class definition other than the default (JDBC), it assumes that ITis responsible for initiating JTA transactions. If you leave the property configuration out, then Hibernate assumes someone else will be responsible (the container).
Not sure when to use/not use, but:
seemed to do the trick for me.