Hi again I can't say that the problem is really solved but we found a screw to turn that the error doesn't occur any longer... within our application ear in the involved jar's --> meta-inf --> jboss-cmp-jdbc.xml we changed the read-ahead strategy from "on-find" to "on-load" and now it's working again. Just came to it, while reading some comments in the jms config-file and JBoss-Wiki, that MySQL has some troubles reading more than one BLOB and therefore the "RecoverMessagesChunk" attribute can be set to 1. So our jar's jboss-cmp-jdbc.xml is now starting with this defaults: <defaults> | <datasource>java:/AFPSDB</datasource> | <create-table>false</create-table> | <remove-table>false</remove-table> | <row-locking>false</row-locking> | <read-ahead> | <strategy>on-load</strategy> | <page-size>1000</page-size> | <eager-load-group>*</eager-load-group> | </read-ahead> | <list-cache-max>1000</list-cache-max> | <clean-read-ahead-on-load>false</clean-read-ahead-on-load> | <entity-command name="no-select-before-insert"/> | </defaults> now it's working again. But I guess it's not the real solution, so perhaps someone could clarify, if it's more a JBoss Bug (as it worked in 4.0.2 with "on-find") or a MySQL JDBC-Driver Problem (although direct SQL via JDBC is working fine). So I think JBoss 4.2.2 Problem!!?!?! thanks (to anyone who at least thought that problem but had no idea ) C-Box View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4153312#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...