 <p>On further analysis, I found that the error boils up to an IOException in the Persistence class. The class <code>ErrorNode</code> must implement <code>Serializable</code> and that should do the trick</p> <blockquote> <p><strong>EDIT:</strong> If you are a jbpm developer, you may want to look at the above error trace that does not give an indication that it is in fact a serialization error on the programmers side that resulted in this error. The actual exception does not propagate to the output.</p> </blockquote>