In some cases XFire client calls to other servers failed with a NPE. Surprisingly that occured only in some configurations when calls where made from code that was deployed in an OC4J container. Reason for the NPE: W3CNamespaceContext.getPrefix(Element e, String uri) does not check if the result 'org.w3c.dom.Element.getAttributes()' is a null. The next line uses the returned object and fails if it was null. I added the null-check and the code works fine - even in OC4J The patched class is attached to this report.