Hi, I'm currently integrating drools (via the .spi.* classes, not via .drl files etc) into our product, and found a very odd class cast exception when producing different rules. java.lang.ClassCastException: org.drools.reteoo.AlphaNode$AlphaMemory cannot be cast to org.drools.reteoo.BetaMemory at org.drools.reteoo.NotNode.assertLeftTuple(NotNode.java:96) at org.drools.reteoo.CompositeLeftTupleSinkAdapter.doPropagateAssertLeftTuple(CompositeLeftTupleSinkAdapter.java:145) at org.drools.reteoo.CompositeLeftTupleSinkAdapter.createAndPropagateAssertLeftTuple(CompositeLeftTupleSinkAdapter.java:57) at org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:142) at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:42) at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:184) at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:146) at org.drools.reteoo.Rete.assertObject(Rete.java:113) at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:218) at org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction.execute(ReteooWorkingMemory.java:291) at org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1475) at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:676) at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:649) at drools.scratch.RecyclingTest.assertSession(RecyclingTest.java:88) Attached you'll find a maven project exhibiting the error, and from stepping through the code pieces it looks like two nodes in the network have the same id. The id was marked as released in the removeRule() process. This is against the 5.0.0.SNAPSHOT. Am I doing something wrong? Missing anything? Or is this a real "blocker" bug? Should I open a JIRA issue for that? Regards, -- Andreas -- Never attribute to malice that which can be adequately explained by stupidity. -- Hanlon's Razor