Great, Several things. You post you end a task in a timer. Looking at the code you don't (anymore) So that is impossible to check. Second, the error post occurs while while retrieving a task list, not when ending a task. Could it be you have multiple threads or something? Besides that, I see you get the exception from the main thread? Are there two jbpm instances running on the same database? Or is your scheduler an external process? The error now is in a completely Again, post a unit test with a process definition that is stripped of all unneeded things. One thing I see that something goes wrong in retrieving a tasklist. at com.jeppesen.sabertooth.workflow.ProcessInstanceBean.getActorTaskList(ProcessInstanceBean.java:1 | 82) Do you do that in the assignment handler to achieve some kind of workloadbalancing? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3965361#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...