User development, A new message was posted in the thread "How a pass signal from state a task or java?? I do not under": http://community.jboss.org/message/520343#520343 Author : Andy Barreras Profile : http://community.jboss.org/people/FlyNavy Message: -------------------------------------------------------------- I was having the same issue.  I believe that the reason was that I was calling a listener on the wrong state event:      <state g="137,123,150,52" name="Generate Visibilities">         <on event="start">         <event-listener class="com.boeing.ids.sogs.gmpwf.listeners.VisibilityListener" />         </on>       <transition g="-143,-10" name="to Check Out Time Segment" to="Check Out Time Segment"/>       <transition name="to cancel" to="cancel" g="-48,-18"/>       <transition name="to error" to="error" g="-42,-18"/>    </state>   Within the listener, I was doing some external work then calling the executionService.signalExecutionById()method.  I think the reason it was failing was because I was calling this method within the state's start event.  In jBPM, you can't trigger a transition to another state until the (current) state execution stops.  When I changed the jpdl code to call the listener on the state's end event, the exception went away:      <state g="137,123,150,52" name="Generate Visibilities">          <on event="end">          <event-listener class="com.boeing.ids.sogs.gmpwf.listeners.VisibilityListener" />          </on>        <transition g="-143,-10" name="to Check Out Time Segment" to="Check Out Time Segment"/>        <transition name="to cancel" to="cancel" g="-48,-18"/>        <transition name="to error" to="error" g="-42,-18"/>     </state>   Hope this helps. -------------------------------------------------------------- To reply to this message visit the message page: http://community.jboss.org/message/520343#520343