Edson, Many thanks for this: yes, we do use serialization so I will try and identify the exact case where this error happens. Cheerio, Nic Nicholas Hemley Senior Developer Sidonis | Powering a New Generation of Service Assurance e: nic.hemley(a)sidonis.com <mailto:carol.hopperton@sidonis.com> m: +44 (0)7956 695 037 t: +44 (0)1225 446060 skype: nicholas.hemley w: www.sidonis.com <http://www.sidonis.com/> sidlogol esig Sidonis Limited. Registered No: 5718402. Registered Office: 2-4 Henry Street, Bath, Somerset. BA1 1JT. VAT Registration No: 879658932. This e-mail and the information it contains may be confidential, legally privileged and protected by law. Access by the intended recipient only is authorised. If you are not the intended recipient, please notify the sender immediately and delete this e-mail from your system. Any review, distribution, reproduction, publication or other use of this e-mail by persons or entities other than the intended recipient is prohibited. From: rules-users-bounces(a)lists.jboss.org [mailto:rules-users-bounces@lists.jboss.org] On Behalf Of Edson Tirelli Sent: 20 October 2009 15:18 To: Rules Users List Subject: Re: [rules-users] ClassCastException - org.drools.reteoo.BetaMemory This is a bug. Would you please open a JIRA and attach as much information about the scenario as you can? A test case would be ideal, even if the problem does not happen every single run. Also, are you using serialization in your application? Edson 2009/10/20 Nicholas Hemley <nic.hemley(a)sidonis.com&gt; Hello, I am getting the following intermittent error from drools 5.0.1 when removing a knowledge package from a knowledge base: org.drools.reteoo.BetaMemory cannot be cast to org.drools.reteoo.RuleTerminalNode$TerminalNodeMemory I iterate over knowledgeBase.getKnowledgePackages() and the error occurs, but only occasionally. The full trace is as follows: java.lang.ClassCastException: org.drools.reteoo.BetaMemory cannot be cast to org.drools.reteoo.RuleTerminalNode$TerminalNodeMemory at org.drools.reteoo.RuleTerminalNode.doRemove(RuleTerminalNode.java:357) at org.drools.common.BaseNode.remove(BaseNode.java:95) at org.drools.reteoo.ReteooBuilder.removeRule(ReteooBuilder.java:237) at org.drools.reteoo.ReteooRuleBase.removeRule(ReteooRuleBase.java:366) at org.drools.common.AbstractRuleBase.removeRule(AbstractRuleBase.java:712) at org.drools.common.AbstractRuleBase.removePackage(AbstractRuleBase.java:640) at org.drools.impl.KnowledgeBaseImpl.removeKnowledgePackage(KnowledgeBaseImpl.j ava:166) Any ideas why this would potentially happen? Cheerio, Nic Nicholas Hemley Senior Developer Sidonis | Powering a New Generation of Service Assurance _______________________________________________ rules-users mailing list rules-users(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-users -- Edson Tirelli JBoss Drools Core Development JBoss by Red Hat @ www.jboss.com