I get this error at runtime for my application deployed on JBoss 4.0.5 which has hibernate 3. java.lang.IncompatibleClassChangeError at org.hibernate.impl.SessionImpl.afterTransactionCompletion(SessionImpl.java:377) at org.hibernate.jdbc.JDBCContext.afterTransactionCompletion(JDBCContext.java:228) at org.hibernate.jdbc.JDBCContext.disconnect(JDBCContext.java:191) at org.hibernate.jdbc.JDBCContext.release(JDBCContext.java:88) at org.hibernate.impl.SessionImpl.close(SessionImpl.java:274) The same configuration deploys fine on JBoss 4.0.2. I tried googling and removed log4j jars (incompatible versions probably) from my application.war file but the problem still persisits what next? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3986683#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...