<min-pool-size>50</min-pool-size> | <max-pool-size>75</max-pool-size> Thats a good enough pool size. What does your application do? Does it heavily use connections. How long are these connections kept open? If i remember correctly, using the jmx-console there is a way to find out the number of connection currently in use, for your datasource. Have you checked this current connection count when this exception occurs? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3959787#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...