I just switched the web.xml to servlet 3.0 (from a app running 2.4 previously) and now I'm seeing the following error (turned on fine logging for org.apache.tomcat.util):
mtyson FINE: Scanning JAR [file:/usr/java/jdk1.6.0_22/jre/lib/ext/jcharset.jar] from classpath
mtyson Jul 19, 2011 10:04:40 AM org.apache.catalina.startup.HostConfig deployDirectory
mtyson SEVERE: Error deploying web application directory ROOT
mtyson org.apache.tomcat.util.bcel.classfile.ClassFormatException: Invalid byte tag in constant pool: 60
UPDATE: Just Tried tomcat 7.0.19 - same results
It may not be your issue, but mine was the same as this one -- an old version of com.ibm.icu:icu4j
. I solved the problem by changing my build configuration to exclude the older transitive dependencies and explicitly depending upon the latest version (4.8).