You mentioned that you run your client in your workspace. You might have some jar files which contain older versions of some classes which axis uses now. For example, I encounter a similar problem because my workspace contains jaxm.jar(from 2003) which has the same set of classes as saaj.jar which comes with axis. As soon as I removed the jaxm.jar, everything runs fine. I even wrote a utility myself to inspect jar files under a directry and list which classes apear in more than one jar files.