As a work-around, I have put | @TransactionAttribute(TransactionAttributeType.NEVER) | on the timer. This seems to stop the exception from being thrown. In this case it's not a problem for me as I can ensure the data integrity by hand quite easily. But I'm not really sure what I've done wrong, as I think you should be able to call a session bean from a timer. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4129692#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...