I've found the solution. The jbpm.cfg.xml was incorrect. Service 'persistence' was : <service name="persistence" factory="org.jbpm.persistence.jta.JtaDbPersistenceServiceFactory" /> instead of : <service name="persistence"> | <factory> | <bean class="org.jbpm.persistence.db.DbPersistenceServiceFactory"> | <field name="isTransactionEnabled"><false/></field> | </bean> | </factory> | </service> and that was causing many different problems like closed session, ClassCastException etc. Regards, View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4252580#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...