[rules-users] JBRULES-2796 - NullPointerException in FromNode.destroyCreatedHandles

[Gareth Evans]

Hello,

I think I am getting the same/similar problem as described in  
JBRULES-2796. I am using Drools 5.1.1 with Expert and Flow, here is  
the stack trace:

Caused by: java.lang.NullPointerException
	at org.drools.reteoo.FromNode.destroyCreatedHandles(FromNode.java:336)
	at org.drools.reteoo.FromNode.retractLeftTuple(FromNode.java:326)
	at  
org 
.drools 
.reteoo 
.CompositeLeftTupleSinkAdapter 
.doPropagateRetractLeftTuple(CompositeLeftTupleSinkAdapter.java:238)
	at  
org 
.drools 
.reteoo 
.CompositeLeftTupleSinkAdapter 
.propagateRetractRightTuple(CompositeLeftTupleSinkAdapter.java:155)
	at org.drools.reteoo.JoinNode.retractRightTuple(JoinNode.java:151)
	at org.drools.reteoo.ObjectTypeNode.retractObject(ObjectTypeNode.java: 
232)
	at org.drools.reteoo.EntryPointNode.retractObject(EntryPointNode.java: 
231)
	at  
org 
.drools 
.common.AbstractWorkingMemory.retract(AbstractWorkingMemory.java:1288)
	at  
org 
.drools 
.base.DefaultKnowledgeHelper.retract(DefaultKnowledgeHelper.java:201)
	at  
org 
.drools 
.base.DefaultKnowledgeHelper.retract(DefaultKnowledgeHelper.java:214)
	at  
procs 
.Rule_my_business_rule_0 
.defaultConsequence(Rule_my_business_rule_0.java:8)
	at  
procs 
.Rule_my_business_rule_0DefaultConsequenceInvoker 
.evaluate(Rule_my_business_rule_0DefaultConsequenceInvoker.java:29)
	at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java: 
917)

The stack trace is different to the one in JBRULES-2796 in that mine  
is caused by a retract rather than an update.

We've created several Flows and associated rules and this issue has  
only just come up with a recently created one.

Firstly, is this the same issue?

If it is, where could I find previous releases of Drools so that I may  
try to downgrade? Alternatively is there some 5.1 -> 5.2 migration  
documentation?

I have tried rewriting the rule that triggers this as there was a  
comment on rules-dev that this made the error go away though I am  
having trouble coming up with different ways to write it as it is  
quite a simple rule. Is there something specific I should try to avoid?

-- 
Gareth Evans
Application Developer
Geneoz Pty Ltd
http://www.geneoz.com
gevans at geneoz.com

+61 8 9212 2200  (Phone)
+61 8 9212 2299  (Fax)

PO Box 1128
Bentley DC, WA 6983
AUSTRALIA

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geneoz VMS
The Vivarium Management Solution
http://www.geneoz.com

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