thanks for your help, So this error occurs when you are trying to build the "default" package in Guvnor? Yes. The process you are adding to Guvnor, which one is that? Could you share that with us? is a simple hello world <?xml version="1.0" encoding="UTF-8"?> <process xmlns="http://drools.org/drools-5.0/process" xmlns:xs="http://www.w3.org/2001/XMLSchema-instance" xs:schemaLocation="http://drools.org/drools-5.0/processdrools-proces... type="RuleFlow" name="ruleflow" id="com.sample.ruleflow" package-name="com.sample" > <header> </header> <nodes> <start id="1" name="Start" x="16" y="16" width="48" height="48" /> <actionNode id="2" name="Hello" x="96" y="16" width="80" height="48" > <action type="expression" dialect="mvel" >System.out.println("Hello World");</action> </actionNode> <end id="3" name="End" x="226" y="14" width="48" height="48" /> </nodes> <connections> <connection from="1" to="2" /> <connection from="2" to="3" /> </connections> </process> Another antecedent. When add hellow_world.rf to Guvnor to 'defaultPackage' and build this packet, everything works properly. 'defaultPackage' has already been created. 'defualt' I define it. Thx eugenio