I stumbled into the same problem. The following did the trick (at least in my environment): In NetBeans IDE 6.0 RC 1: 1. select top-level menu "Tools" -> "Servers" 2. select the "Glassfish" server and the "Options" tab 3. uncheck the "Directory Deployment Enabled" option The "Help Information" for this option says: "Directory Deployment Enabled. When selected, web, EJB and EAR projects are deployed to the server from the build directory. This can reduce deployment time. This option is selected by default." It seams that Glassfish somehow get's confused with jboss-seam.jar if loaded from the build directory. I didn't go deeper down into invenstigation - just accepting that the "unchecked option" and normal deployment through the "ear-file" works fine. / Regards Peter Jervgren View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4107254#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...