Hello, I have a server running tomcat 4.0 beta 7. I put on it an application that sends email, so mail.jar is in the WEB-INF/lib directory. I got a very unuseful error message when accessing the relevant JSP: Root Cause: java.lang.NumberFormatException: Could not find package named at java.lang.Throwable.(Throwable.java:96) at java.lang.Exception.(Exception.java:44) at java.lang.RuntimeException.(RuntimeException.java:49) etc...... The problem is that to find out what was wrong I had to move the application to my desktop PC which is running tomcat 4.0 beta 6. This produced a far superior error message that made it clear that I had forgotten to put activation.jar into the WEB-INF/lib directory (required for javamail). If you want any more detail on these messages get back to me. I would be very grateful if future tomcat 4s can revert to helpful error messages in this situation. Regards, Peter Joanes [EMAIL PROTECTED]