Hi, sorry for last post following is the right post I am migrating my application from Tomcat to jboss-4.2.2.GA, I did the configuration but still I am getting NoClassDefFound Exception, same thing is working properly with Tomcat. I gone through the document for jboss configuration i did that also still i am getting NoClassDefFoundException. I also did one more thing i used UnifiedClassLoader3 is given as below for this I am getting ClassCastException. UnifiedClassLoader3 actualClassLoader = (UnifiedClassLoader3) Thread.currentThread().getContextClassLoader(); actualClassLoader.addURL(new URL(System.getProperty("jboss.server.config.url")+ "linkmanager/models/services/")); cls = actualClassLoader.loadClass(annotationclass, true); After doing all this stuff still this problem is not resolved from last one week. can any body help me to resolve this problem of classloader. Thanks in Advance Ashish Rai View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4155941#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...