I'm using drools 5.5.0.Final. I noticed that I got the bellow exception in my logs, but my process is finished. I mean that this exception wasn't break the process, only logged out. what is the meaning of this exception and how can I resolve it. I tried to upgrade mvel2 to the latest final version (2.1.8.Final) but it wasn't solve the exception. java.lang.RuntimeException: Unknown accessor type: org.mvel2.optimizers.impl.refl.collection.ArrayCreator@5b8452eb at org.drools.rule.constraint.ConditionAnalyzer.analyzeAccessor(ConditionAnalyzer.java:264) at org.drools.rule.constraint.ConditionAnalyzer.analyzeNode(ConditionAnalyzer.java:250) at org.drools.rule.constraint.ConditionAnalyzer.statementToExpression(ConditionAnalyzer.java:467) at org.drools.rule.constraint.ConditionAnalyzer.readInvocationParams(ConditionAnalyzer.java:450) at org.drools.rule.constraint.ConditionAnalyzer.analyzeAccessor(ConditionAnalyzer.java:345) at org.drools.rule.constraint.ConditionAnalyzer.analyzeExpressionNode(ConditionAnalyzer.java:326) at org.drools.rule.constraint.ConditionAnalyzer.analyzeAccessor(ConditionAnalyzer.java:286) at org.drools.rule.constraint.ConditionAnalyzer.analyzeNode(ConditionAnalyzer.java:250) at org.drools.rule.constraint.ConditionAnalyzer.analyzeSingleCondition(ConditionAnalyzer.java:133) at org.drools.rule.constraint.ConditionAnalyzer.analyzeCondition(ConditionAnalyzer.java:99) at org.drools.rule.constraint.ConditionAnalyzer.analyzeCondition(ConditionAnalyzer.java:70) at org.drools.rule.constraint.MvelConditionEvaluator.getAnalyzedCondition(MvelConditionEvaluator.java:83) at org.drools.rule.constraint.MvelConstraint.executeJitting(MvelConstraint.java:270) at org.drools.rule.constraint.MvelConstraint.access$200(MvelConstraint.java:51) at org.drools.rule.constraint.MvelConstraint$ConditionJitter.run(MvelConstraint.java:250) at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) at java.lang.Thread.run(Thread.java:662) -- View this message in context: http://drools.46999.n3.nabble.com/how-can-I-resolve-java-lang-RuntimeExce... Sent from the Drools: User forum mailing list archive at Nabble.com.