As it says on the WIKI, prefill only works if you use the single pool option which are using but should not. If your MCF has a required CRI then JBoss doesn't know what that should be (the contents are opaque to the connection manager - see the spec). And as the FAQ says you should be using the "incorrectly named" <application-managed-security/> if you have request parameters - a ConnectionRequestInfo (CRI). The "workaround" is to tell it what the CRI is by programmatically asking for a connection with the correct request parameters, see the original feature request (also linked on the WIKI page describing the prefill option) http://wiki.jboss.org/wiki/Wiki.jsp?page=JBossJCAPooling View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4130794#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...