The "Bad version number in .class file" is the error message you get when you try running a class compiled with the 1.6 compiler with a 1.5 JVM. Either recompile with 1.5, or run with 1.6. Complaint: the error message used to give the class version numbers so that you at least had a clue what went wrong. Someone must have complained that the class version number (48 for 1.4 and 49 for 1.5, I think) didn't match the release number so Sun did the easy thing - dropped the number from the error message. Boo. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4106484#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...