[rules-users] Guvnor only: NullPointerException AfterEvaluator.evaluateCachedRight

[kappert]

Version 5.5.0.Final (Guvnor and libraries)

We are seeing the NPE with the stack trace given below, but only when
loading rules through Guvnor. Same rules file and code runs fine without
Guvnor, but error with Guvnor.
*With Guvnor:*  KnowlegdeBase from KnowledgeAgent using changeset.xml,
scanner running for on-the-fly rule updates in Guvnor.
*Without Guvnor:* kbuilder.add(new ClassPathResource("Rules.drl",
getClass()), ResourceType.DRL);

I have only little experience with Drools and would appreciate advice on how
to approach this problem.

Could it be something in the rules file itself?
But why would it make a difference whether the rules came from Guvnor or a
file?
Could the error point to something missing from the POJO model in Guvnor? I
am still in the process of determining what should go in the JAR file
exported from Eclipse and what not. The rules validate OK in Guvnor though,
and the package can be built.
What else to consider?

A  similar problem was discussed here
<http://thread.gmane.org/gmane.comp.java.drools.user/15285>  , but the
solution seems to have been an upgrade to version 5.



Unexpected exception caught: null
java.lang.NullPointerException
	at
org.drools.base.evaluators.AfterEvaluatorDefinition$AfterEvaluator.evaluateCachedRight(AfterEvaluatorDefinition.java:322)
	at
org.drools.rule.constraint.EvaluatorConstraint.isAllowedCachedRight(EvaluatorConstraint.java:80)
	at
org.drools.common.TripleBetaConstraints.isAllowedCachedRight(TripleBetaConstraints.java:101)
	at org.drools.reteoo.JoinNode.propagateFromRight(JoinNode.java:156)
	at org.drools.reteoo.JoinNode.assertObject(JoinNode.java:148)
	at
org.drools.reteoo.CompositeObjectSinkAdapter.doPropagateAssertObject(CompositeObjectSinkAdapter.java:497)
	at
org.drools.reteoo.CompositeObjectSinkAdapter.propagateAssertObject(CompositeObjectSinkAdapter.java:382)
	at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:235)
	at org.drools.reteoo.EntryPointNode.assertObject(EntryPointNode.java:240)
	at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:350)
	at org.drools.common.NamedEntryPoint.insert(NamedEntryPoint.java:311)
	at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:903)
	at
org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:847)
	at
org.drools.impl.StatefulKnowledgeSessionImpl.insert(StatefulKnowledgeSessionImpl.java:269)



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