I have the same problem. Keep getting this error.
I have found that putting @Transactional on the method or JavaBean where you are using jbpm helps.
Try that and see what happens
Thank you for your advice. But it seems to me not more than an ugly hacking workaround on a problem which should be solved somewhere else (within JBPM itself?). The problem only arises if I want to see the seam debug page, and this is not a production issue. Putting Transactional annotations throughout the code, without even knowing exactly what for, is definitely not an option for the productive code.