I have a similar issue and I think there is a race condition between the DispatcherThread that handles the execution of async Messages/Jobs and the main-Thread. Both alter data in the JBPM4_JOB table, I think this is what is going on:
- main-Thread is running along, minding his own business and creates a hibernate-Session
- DispatcherThread wakes up and also creates a hibernate-Session accessing data in the JBPM4_JOB table
- DispatcherThread did its work and removes the Job data from the JBPM4_JOB table
- main-Thread ends an execution and deletes the execution related data from the JBPM4_JOB table,
since the same data have been altered by different session there is an exception at this point