I'm trying to upgrade a perfectly running embedded Tomcat 5.5 to Tomcat 6.0. I understand that all I need to do is replace Tomcat 5.5 jars with 6.0. That's what I did. So I replaced the following jars: catalina-5.0.28.jar catalina-5.5.9.jar catalina-optional-5.5.9.jar commons-el.jar commons-modeler-1.1.0.jar jasper-compiler-jdt.jar …