When you shutdown the app server, Hypersonic creates two files in the server/xxx/data/hypersonic directory (where xxx is the configuration name, such as 'default'). It would appear that one or both of those files has been corrupted. You can remove that directory and the app server should start without errors. Of course you will lose any data that was stored in that database, but then you should not use Hypersonic to store important data anyway. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4061741#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...