PROBLEM SOLVED : Apparently jBPM cannot use a timer when the corresponding process definition has only been instantiated in memory from an XML definition but has not been persisted (at least in the Hibernate L1 cache if not in the DB). When I add this call after instantiating the process definition, I don't get the Hibernate transient exception anymore : jbpmContext.deployProcessDefinition(processDefinition); View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4087306#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...