I've created the following rule in BRMS and deployed it - rule "Underwriting Rule 1" dialect "mvel" when p : Policy( premium < "50.00" ) then p.setStatus( 32 ); end I have the following code processing the rule - public void main(Policy inputPolicy) throws Exception { RuleBase ruleBase = loadRuleBase(); StatefulSession session = ruleBase.newStatefulSession(); session.insert(inputPolicy); session.fireAllRules(); } private RuleBase loadRuleBase() throws IOException, Exception { RuleAgent agent = RuleAgent.newRuleAgent("/uwrules.properties"); RuleBase ruleBase = agent.getRuleBase(); return ruleBase; } When I run my application I get the following error. Could someone tell me why or where to look to determine the reason? Do I have something coded incorrectly? Exception in thread "main" javax.ejb.EJBException: java.lang.ClassCastException: java.util.HashSet at org.jboss.ejb3.tx.Ejb3TxPolicy.handleExceptionInOurTx(Ejb3TxPolicy.java:63) at org.jboss.aspects.tx.TxPolicy.invokeInOurTx(TxPolicy.java:83) at org.jboss.aspects.tx.TxInterceptor$Required.invoke(TxInterceptor.java:191) . . . Caused by: java.lang.ClassCastException: java.util.HashSet at org.drools.rule.Package.readExternal(Package.java:172) at java.io.ObjectInputStream.readExternalData(Unknown Source) at java.io.ObjectInputStream.readOrdinaryObject(Unknown Source) at java.io.ObjectInputStream.readObject0(Unknown Source) at java.io.ObjectInputStream.readObject(Unknown Source) at org.drools.agent.HttpClientImpl.fetchPackage(HttpClientImpl.java:54) at org.drools.agent.URLScanner.readPackage(URLScanner.java:137) at org.drools.agent.URLScanner.getChangeSet(URLScanner.java:109) at org.drools.agent.URLScanner.loadPackageChanges(URLScanner.java:88) at org.drools.agent.RuleAgent.checkForChanges(RuleAgent.java:297) at org.drools.agent.RuleAgent.refreshRuleBase(RuleAgent.java:265) at org.drools.agent.RuleAgent.configure(RuleAgent.java:251) at org.drools.agent.RuleAgent.init(RuleAgent.java:183) at org.drools.agent.RuleAgent.newRuleAgent(RuleAgent.java:192)