Ok, i've found it! Since the new jboss ts implementation supports only one local-tx-resource per distributed transaction, the timer can not be commited until a bean uses more then one local-tx resource. Timers are hosted by default within the non xa hsqldb. So if we use in our transaction also one another local-tx data source, the exception above occurs! I've switched from local-tx to xa data source and the timers work fine! View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4042678#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...