Well, well... Sorry for so many messages, but since I can't edit mine, I've to add one after another and so on :P . I've found a solution to use the last version of that JARs and without JBoss complaining because of it. First of all, I've realized that the 3 JARs included in "lib/endorsed" are just the content of the "Xalan-J" package from Apache (which includes "xercesImpl.jar" of course). I already got in my local repository the last version of Xalan. So I've just made a backup of "endorsed" and made a new one with the content of the last Xalan. I've turned on JBoss, and everything has worked fine. Another workaround which I've discovered is to change the value of the JBOSS_ENDORSED_DIRS environment variable in several of the "bin/*.sh" or "bin/*.bat" files and make it point to a personal directory which include the most recent JARs of Xalan-J. The only problem of doing all this is that you won't be able to use different versions of Xerces at the same time. Fortunately I've tried to duplicate in my project more JARs used by JBoss and they don't cause any problem. Even different versions of "xalan.jar" or "serializer.jar" can be used isolated in every project. So, summarizing a lot, this problem seems to be exclusive of "xercesImpl.jar". And, sincerely, I doubt that I can't live with only 1 version of it. I'll use a common. If you have any alternative idea about this, let me know ;) . View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4229575#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...