On occasion we'll get this exception. This is thrown to indicate that a row in the database that was recently inserted was not actually inserted (used to retrieve generated properties). The cause of this problem is the Connection does not return the correct value for getGeneratedKeys(). This is most likely caused because the Connection is being shared and therefore the value held by the database is either lost or overwritten by the concurrent user of the Connection. We never get this error when using Tomcat (DBCP) but when we use Jetty we'll get this every once in a while. We're using the same connection pooling as Tomcat. Has anyone else encountered this problem?