anonymous wrote : | but haven't touched jms-ds.xml or standardjboss.xml | Yes, I believe this is the issue. Again, please post your jms-ds.xml file and your standardjboss.xml file, at the very least, please post the portion of your jms-ds.xml file that references your provider loader. Chances are your new *-ds.xml file contains the line: org.jboss.jms.jndi.JBossMQProvider This was changed in JBoss 4.0.x. To org.jboss.jms.jndi.JNDIProviderAdapter There is a discrepancy somewhere. Again, this has nothing to do with your NoTxDataSource. The error is telling you that the DLQ handler for your MDB cannot be setup because the XAConnectionFactory cannot be found. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3980194#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...