Hi Marius, I did more testing. The problem is becoming more specific. I tried both spring deployer release 2 and release 3. It contains | jboss-spring-jdk5.jar | spring-aop.jar | spring-beans.jar | spring-context.jar | spring-core.jar | I am not clear which version of the spring framework come along with depoyer (say version 3). After I replaced spring jars in default/lib with them, it is okay to deploy my spring archive. However it doesn't work with spring-web.jar, which come from spring framework package. It seems the the spring-web.jar (from spring framework) and other spring jar files (from deployer) are incompatible. Can you please tell me which spring-web.jar work well with spring jar files (along with spring deployer release 3)? I also replaced spring jar files with spring framework 2.5.5 or 2.0.8 or 1.0.8, it turns out the spring deployer couldn't find DefaultXmlBeanDefinitionParser. | java.lang.NoClassDefFoundError: org/springframework/beans/factory/xml/DefaultXmlBeanDefinitionParser | Yes, DefaultXmlBeanDefinitionParser doesn't exist in any of above spring frameworks. It seems that the spring jar files in the deployer are customized somehow. Can you verify that as well? How can I solve this incompatible problem? Thanks, View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4266817#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...