First, there should be stack traces in the console log or in server.log that correspond to the errors you mentioned. Post one of thos stack traces. The max-pool-size seems very low. How likely is it that an HTTP request will need a database connection? If every request needs a connection, then max-pool-size should be closer to maxThreads. Most likely what happened for the 500 error is that too many HTTP requests were waiting for a database connection and thus were turned away. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4256670#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...