See Thread at: http://www.techienuggets.com/Detail?tx=87016 Posted on behalf of a User May be appropriate Ant version need, according to jbpm userguide that is 1.7+. I've faced with the same problem with ant <1.7. In Response To: Hi All, I am running c:\jbpm-4.0.0.Beta2\jboss>ant demo.setup and it is failing with the following error BUILD FAILED C:\jbpm-4.0.0.Beta2\jboss\build.xml:54: The following err or occurred while executing this line: java.lang.AbstractMethodError: org.apache.xerces.dom.ElementNSImpl.setUserData(L java/lang/String;Ljava/lang/Object;Lorg/w3c/dom/UserDataHandler;)Ljava/lang/Obje ct; Total time: 2 minutes 3 seconds I am using java version "1.5.0_07". Any suggestions. I have downloaded jboss-5.0.0.GA.zip and eclipse-jee-ganymede-SR2-win32.zip into the downloads directory - C:\jbpm-4.0.0.Beta2\downloads thanks Neal