When UnavailableException is thrown from the Servlet:init, Tomcat doesn't output the stack trace of UnavailableException. The cause of problem is lost. Tomcat should output the stack trace at the "invoke" method of StandardWrapperValue.
Created attachment 19907 [details] Tomcat outputs the stack trace with this patch. Tomcat outputs the stack trace with this patch.
Your patch has been applied to svn and will be included in 5.5.24 and 6.0.12 onwards. Many thanks.