User development, A new message was posted in the thread "Issue specifying the &lt;jar-file&gt; in persistence.xml in JBOSS 5 on linux system": http://community.jboss.org/message/519603#519603 Author : Dragos Bobes Profile : http://community.jboss.org/people/dbobes Message: -------------------------------------------------------------- It is in the root of the ear file. In fact in my examples myseammodule.jar = myejbmodule.jar but I lost track of the name I used during my trials. If I specify directly the jar file it works fine on the linux system but it doesn't work in windows anymore.   .... <jar-file>myejbmodule.jar</jar-file> ...   You can use the first file I uploded in the previous reply (http://community.jboss.org/servlet/JiveServlet/download/519363-7250/myapp...) to test this issue. Just modify the persistence.xml and you'll see that jboss on windows doesn't like this path specification. -------------------------------------------------------------- To reply to this message visit the message page: http://community.jboss.org/message/519603#519603