I have got this error when I tried to access the Tomcat welcome page
Perry Tew This is caused by mismatched versions of jars used by Tomcat. I've encountered this error before when I've done upgraded tomcat and failed to remove old jars from my classpath ( like servlet.jar, etc). It happens when tomcat attempts to call a new method that is not found in older jars. If you download a fresh version of tomcat and copy over your existing jars, you should sync up your system. A better idea would be to download a fresh version of tomcat and just use that version completely.