Below is a self-contained DRL which, when run with 5.5.0, throws an exception "cannot invoke method asList". Remarkably, this only happens when a second Project fact is inserted. (Haven't I heard this before?) -W import java.util.List; import java.util.Arrays; import java.util.ArrayList; declare Project @typesafe (false) list1 : List list2 : List end rule kickoff salience 999999 when then insert( new Project() ); insert( new Project() ); // necessary to trigger the exception end rule " Config rule " dialect "mvel" no-loop true when P : Project() then modify(P) { list1 = Arrays.asList(10, 15, 20, 25), list2 = Arrays.asList(11, 2, 3, 4, 5, 10, 9, 8, 7) }; end Exception in thread "main" Exception executing consequence for rule " Config rule " in express: java.lang.RuntimeException: cannot construct object at org.drools.runtime.rule.impl.DefaultConsequenceExceptionHandler.handleException(DefaultConsequenceExceptionHandler.java:39) at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1297) at org.drools.common.DefaultAgenda.fireNextItem(DefaultAgenda.java:1221) at org.drools.common.DefaultAgenda.fireAllRules(DefaultAgenda.java:1456) at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:710) at org.drools.common.AbstractWorkingMemory.fireAllRules(AbstractWorkingMemory.java:674) at org.drools.impl.StatefulKnowledgeSessionImpl.fireAllRules(StatefulKnowledgeSessionImpl.java:230) at express.Main.execute(Main.java:77) at express.Main.main(Main.java:110) Caused by: java.lang.RuntimeException: cannot construct object at org.mvel2.optimizers.impl.refl.nodes.ConstructorAccessor.getValue(ConstructorAccessor.java:63) at org.mvel2.ast.NewObjectNode.getReducedValueAccelerated(NewObjectNode.java:233) at org.mvel2.compiler.ExecutableAccessor.getValue(ExecutableAccessor.java:42) at org.mvel2.ast.WithNode$ParmValuePair.eval(WithNode.java:281) at org.mvel2.ast.WithNode.getReducedValueAccelerated(WithNode.java:67) at org.mvel2.ast.InterceptorWrapper.getReducedValueAccelerated(InterceptorWrapper.java:40) at org.mvel2.MVELRuntime.execute(MVELRuntime.java:85) at org.mvel2.compiler.CompiledExpression.getDirectValue(CompiledExpression.java:123) at org.mvel2.compiler.CompiledExpression.getValue(CompiledExpression.java:119) at org.mvel2.MVEL.executeExpression(MVEL.java:930) at org.drools.base.mvel.MVELConsequence.evaluate(MVELConsequence.java:104) at org.drools.common.DefaultAgenda.fireActivation(DefaultAgenda.java:1287) ... 7 more Caused by: java.lang.RuntimeException: cannot invoke method: asList at org.mvel2.optimizers.impl.refl.nodes.MethodAccessor.getValue(MethodAccessor.java:63) at org.mvel2.optimizers.impl.refl.nodes.VariableAccessor.getValue(VariableAccessor.java:37) at org.mvel2.ast.ASTNode.getReducedValueAccelerated(ASTNode.java:108) at org.mvel2.compiler.ExecutableAccessor.getValue(ExecutableAccessor.java:42) at org.mvel2.optimizers.impl.refl.nodes.ConstructorAccessor.executeAll(ConstructorAccessor.java:76) at org.mvel2.optimizers.impl.refl.nodes.ConstructorAccessor.getValue(ConstructorAccessor.java:43) ... 18 more Caused by: java.lang.ArrayIndexOutOfBoundsException: 4 at org.mvel2.optimizers.impl.refl.nodes.MethodAccessor.executeAll(MethodAccessor.java:149) at org.mvel2.optimizers.impl.refl.nodes.MethodAccessor.getValue(MethodAccessor.java:48) ... 23 more _______________________________________________ rules-dev mailing list rules-dev(a)lists.jboss.org https://lists.jboss.org/mailman/listinfo/rules-dev