I’m trying to create StatefulKnowledgeSession: StatefulKnowledgeSession ksession = JPAKnowledgeService.newStatefulKnowledgeSession( kbase, null, env); Here is the problem as it seen in the log: 15:39:05,884 ERROR [STDERR] Caused by: java.lang.IllegalArgumentException: Unable to instantiate process instance manager factory 'org.drools.persistence.processinstance.JPAProcessInstanceManagerFactory' 15:39:05,884 ERROR [STDERR] at org.drools.SessionConfiguration.initProcessInstanceManagerFactory(SessionConfiguration.java:317) 15:39:05,884 ERROR [STDERR] at org.drools.SessionConfiguration.getProcessInstanceManagerFactory(SessionConfiguration.java:291) 15:39:05,884 ERROR [STDERR] at org.drools.common.AbstractWorkingMemory.<init>(AbstractWorkingMemory.java:367) 15:39:05,884 ERROR [STDERR] at org.drools.common.AbstractWorkingMemory.<init>(AbstractWorkingMemory.java:295) 15:39:05,884 ERROR [STDERR] at org.drools.common.AbstractWorkingMemory.<init>(AbstractWorkingMemory.java:259) 15:39:05,884 ERROR [STDERR] at org.drools.reteoo.ReteooWorkingMemory.<init>(ReteooWorkingMemory.java:96) 15:39:05,885 ERROR [STDERR] at org.drools.reteoo.ReteooStatefulSession.<init>(ReteooStatefulSession.java:80) 15:39:05,885 ERROR [STDERR] at org.drools.reteoo.ReteooRuleBase.newStatefulSession(ReteooRuleBase.java:386) 15:39:05,885 ERROR [STDERR] at org.drools.reteoo.ReteooRuleBase.newStatefulSession(ReteooRuleBase.java:371) 15:39:05,885 ERROR [STDERR] at org.drools.persistence.session.SingleSessionCommandService.<init>(SingleSessionCommandService.java:97) Exception is thrown from here: private void initProcessInstanceManagerFactory() { ... if ( clazz != null ) { try { this.processInstanceManagerFactory = clazz.newInstance(); } catch ( Exception e ) { throw new IllegalArgumentException( "Unable to instantiate process instance manager factory '" + className + "'" ); } ... } And the actual Exception type is ClassCastException java.lang.ClassCastException: org.drools.persistence.processinstance.JPAProcessInstanceManagerFactory cannot be cast to org.drools.process.instance.ProcessInstanceManagerFactory I’ve created the following snippet to illustrate the problem: …running inside JTA transaction Class<ProcessInstanceManagerFactory> cls = (Class<ProcessInstanceManagerFactory>) Class.forName("org.drools.persistence.processinstance.JPAProcessInstanceManagerFactory"); // this one is OK ProcessInstanceManagerFactory pimf = (ProcessInstanceManagerFactory)cls.newInstance(); System.out.println(pimf.getClass().getCanonicalName()); cls = (Class<ProcessInstanceManagerFactory>)Thread.currentThread().getContextClassLoader().loadClass("org.drools.persistence.processinstance.JPAProcessInstanceManagerFactory" ); // here will be ClassCastException pimf = (ProcessInstanceManagerFactory)cls.newInstance(); System.out.println(pimf.getClass().getCanonicalName()); It seems that ProcessInstanceManagerFactory interface and JPAProcessInstanceManagerFactory are loaded by different class loaders. How can I avoid that problem? I'm using Drool Flow 5.1.1, JBoss 6.0, Hibernate 3.6.0. -- View this message in context: http://drools-java-rules-engine.46999.n3.nabble.com/ClassCastException-in... Sent from the Drools - User mailing list archive at Nabble.com.