Experienced ClassCastException mixing BetaMemory and AlphaMemory. There is debate in the mailing list/forum. The problem seems to be related to dymanic updates of knowledgebase.

Saddly there is no deterministic way how to reproduce the issue, but that should not prevent tracking it here.

Stack trace from my project:

java.lang.ClassCastException: org.drools.reteoo.BetaMemory cannot be cast to org.drools.reteoo.AlphaNode$AlphaMemory
at org.drools.reteoo.AlphaNode.assertObject(AlphaNode.java:136) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:497) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:382) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:235) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:240) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:350) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:311) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:903) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:192) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.base.DefaultKnowledgeHelper.insert(DefaultKnowledgeHelper.java:186) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at cz.nextiraone.screening.rules.screening.Rule_Telefonni_cislo_z_textu_jen_cifry225b11d6cd07418aac8c06cf5c86b4b1.defaultConsequence(Rule_Telefonni_cislo_z_textujen_cifry_225b11d6cd07418aac8c06cf5c86b4b1.java:7) ~[na
:na]
at cz.nextiraone.screening.rules.screening.Rule_Telefonni_cislo_z_textu_jen_cifry_225b11d6cd07418aac8c06cf5c86b4b1DefaultConsequenceInvokerGenerated.evaluate(Unknown Source) ~[na:na]
at cz.nextiraone.screening.rules.screening.Rule_Telefonni_cislo_z_textu_jen_cifry_225b11d6cd07418aac8c06cf5c86b4b1DefaultConsequenceInvoker.evaluate(Unknown Source) ~[na:na]
at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1287) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1221) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1456) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:674) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]
at org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:230) ~[drools-core-5.5.0.Final.jar:5.5.0.Final]