Once you have completed the last task in the process, the process goes to the end sate after which it is deleted from the jbpm4_execution table and is then put into the JBPM4_HIST_PROCINST table, Now here are the two lines that are causing the problem: this is in the del method: ProcessInstance pi = processEngine.getExecutionService().findProcessInstanceById(this.processInstance.getId()); String executionId = pi.findActiveExecutionIn("end").getId(); The process instance has been deleted, as it has ended. IF it is deleted, the pi object is null and hence it throws a NPE, View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4242561#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...