Our problem is exactly the same as JBPM-681.
However the fix proposed in JBPM-1775 is not working for us.
I will attach a patch that fixes the problem for us.
JBPM-2823 Lazy loading of ExceptionHandler causes Exception in JTA Env
JBPM-681 GraphElement.raiseException results in Exception with Java EE
JBPM-1775 verify if collection exceptionHandlers can be loaded lazy