I'm getting the same problem when trying to deploy a EJB 2.0 MDB. I am using JBoss 7.1.1 final. The ejb-jar.xml specifies the http://java.sun.com/dtd/ejb-jar_2_0.dtd but it seams that jboss is checking against the jboss-as-7.1.1.Final/docs/schema/ejb-jar_2_1.xsd (but the ejb-jar_2_0.dtd is also available in the docs/schema folder.