Check the javadoc for java.lang.LinkageError. Most likely, you are using different Drools versions for compiling the package and using it. -W On 04/05/2012, Zhao Yi <zhaoyi0113@> wrote: > > I have two knowledge bases,one is drl file the other is pkg file. My > application creates knowledge base from drl files first then create > knowledge base from pkg file. There is nothing wrong when I create drl > file > knowledge base and fire rules, but I got below error when I create pkg > file > knowledge and fire the rules. Does anyone know what this issue mean? > > Caused by: java.lang.LinkageError: loader constraint violation: loader > (instance of org/drools/rule/JavaDialectRuntimeData$PackageClassLoader) > previously initiated loading for a different type with name > "org/drools/WorkingMemory" > > -- > View this message in context: > http://drools.46999.n3.nabble.com/working-memory-error-tp3961517.html > Sent from the Drools: User forum mailing list archive at Nabble.com. > _______________________________________________ > rules-users mailing list > rules-users@.jboss > https://lists.jboss.org/mailman/listinfo/rules-users > _______________________________________________ rules-users mailing list rules-users@.jboss https://lists.jboss.org/mailman/listinfo/rules-users