This usually happens when you grab a data source and then fail to close it after you are done with it. For example, within a method for a stateless session bean, if you do: DataSource ds = lookupDataSource(); Connectionn conn = ds.getConnection(); .. do stuff with the database ... return; then you have problems. Instead, you should code as: DataSource ds = getDataSource(); Connectionn conn = ds.getConnection(); try { .. do stuff with the database ... } finally { conn.close(); } return; View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3958627#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...