[rules-users] "java.lang.AbstractMethodError: org.jbpm.marshalling.impl.ProcessMarshallerImpl.init" while unmarshalling statefulknowledgesession

Hi All, I ran across an issue while unmarshalling StatefulKnowledgeSession. First I'm marshalling the session using the following code which works fine Marshaller marshaller = MarshallerFactory .newMarshaller(workingMemory.getKnowledgeBase()); File file = new File( "C:\\Users\\Sumatheja\\workingmemory.info"); FileOutputStream fos = new FileOutputStream(file); ByteArrayOutputStream baos = new ByteArrayOutputStream(); marshaller.marshall(baos, workingMemory); baos.writeTo(fos); baos.close(); When I try to unmarshall the session using Marshaller marshaller = MarshallerFactory .newMarshaller(workingMemory.getKnowledgeBase()); FileInputStream fis = new FileInputStream("C:\\Users\\Sumatheja\\workingmemory.info"); workingMemory = marshaller.unmarshall(fis); I'm getting the Error: java.lang.AbstractMethodError: org.jbpm.marshalling.impl.ProcessMarshallerImpl.init(Lorg/drools/marshalling/impl/MarshallerReaderContext;)V at org.drools.marshalling.impl.PersisterHelper.buildRegistry(PersisterHelper.java:287) at org.drools.marshalling.impl.ProtobufInputMarshaller.loadAndParseSession(ProtobufInputMarshaller.java:219) at org.drools.marshalling.impl.ProtobufInputMarshaller.readSession(ProtobufInputMarshaller.java:152) at org.drools.marshalling.impl.ProtobufMarshaller.unmarshall(ProtobufMarshaller.java:117) at org.drools.marshalling.impl.ProtobufMarshaller.unmarshall(ProtobufMarshaller.java:86) at mattelli.re.ComplianceEngine.ComplianceRunService(ComplianceEngine.java:271) at mattelli.re.ComplianceEngine.main(ComplianceEngine.java:84) No Idea what I'm missing out... any help will be appreciated... Thanks in advance -- cheers Sumatheja Dasararaju