Why does Tomcat fail to startup after upgrading to tomcat5-5.5.23-0jpp.9.el5_5 ?

Issue

• Tomcat crashing on startup after applying errata 'tomcat5-5.5.23-0jpp.9.el5_5'.
• Tomcat fails to start with java.lang.NullPointerException.
• Tomcat fails to start with java.lang.StackOverflowError.
• tomcat5 upgrade to tomcat5-5.5.23-0jpp.9.el5_5 causes exception at start.

The following exception appear in /var/log/tomcat5/catalina.out for java.lang.NullPointerException:

LifecycleException:  Error initializaing :  java.lang.NullPointerException  <----------
        at org.apache.catalina.core.StandardContext.start(StandardContext.java:3986)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1014)
        at org.apache.catalina.core.StandardHost.start(StandardHost.java:736)
        at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1014)
        at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:443)
        at org.apache.catalina.core.StandardService.start(StandardService.java:448)
        at org.apache.catalina.core.StandardServer.start(StandardServer.java:700)
        at org.apache.catalina.startup.Catalina.start(Catalina.java:552)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:616)
        at org.apache.catalina.startup.Bootstrap.start(Bootstrap.java:295)
        at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:433)

Following messages are seen in /var/log/tomcat5/catalina.out for java.lang.StackOverflowError:

XX-XXX-2010 14:15:02 org.apache.catalina.startup.HostConfig checkResources 
WARNING: Error during context [/XXXXX] destroy 
java.lang.StackOverflowError