Hey David, I've misread that earlier - this is *java.lang.NoClassDefFoundError* - which means the class that was available at the compile time is not available now to the JVM.
I suspect it might be a problem with your * com.systemsmadesimple.hibernate.HibernateUtil* class implementation. As per specification (JSE 12.4.2 Detailed Initialization Procedure http://docs.oracle.com/javase/specs/jls/se7/html/jls-12.html#jls-12.4.2) says: "5. If the Class object for C is in an erroneous state, then initialization is not possible. Release LC and throw a NoClassDefFoundError." Now, for some reason that class worked fine on JBoss (that has hibernate and other required libraries packaged already), and now it is failing on Tomcat. I would look into the following things: 1. Contents of the WEB-INF/lib? What libraries? What versions? 2. Contents of CATALINA_HOME/lib? What else is there other than standard libraries? 3. HibernateUtil class implementation 4. How your transaction manager has been configured? This is just a wild guess, it might be that your developers leveraged transaction manager in the static initializer of HibernateUtil class, and that worked on JBoss since *JBossTransactionManagerLookup* is configured in your hibernate.cfg.xml file - now it is failing in Tomcat, and somehow other exceptions/errors are consumed/hidden in try-catch blocks in HibernateUtil class. Do you have access to the HibernateUtil source code? Who is building/packaging this application for you? Hope that helps! Cheers! Neven
