Wow, 5.0.0.Beta1, that's old. Anyway, sometime before 5.0.0.GA the app server became stricter regarding XML file validation, and now if something is out of order it will complain (as you found out). Scanning the JBossAS5 forum will turn up many others with this same issue. One solution is to fix the offending XML file. This wiki article shows another solution (even though the symptoms described are not exactly yours): http://www.jboss.org/community/wiki/JBossAS510CR1failstobootfromIDE View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4250231#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...