jpox.null-value="default" in a boolean field causes: 1.) With MySQL, you won't be able to create and upgrade your database from Continuum 1.2.x to 1.3.x ERROR JPOX.RDBMS - Error thrown executing CREATE TABLE `PROJECTNOTIFIER` ( `ID` INTEGER NOT NULL, `ENABLED` BIT NOT NULL, `NOTIFIERORIGIN` INTEGER NOT NULL, `MODEL_ENCODING` VARCHAR(255) BINARY NULL, `RECIPIENT_TYPE` INTEGER NOT NULL, `SEND_ON_ERROR` BIT NOT NULL, `SEND_ON_FAILURE` BIT NOT NULL, `SEND_ON_SCM_FAILURE` BIT NOT NULL DEFAULT 'false', `SEND_ON_SUCCESS` BIT NOT NULL, `SEND_ON_WARNING` BIT NOT NULL, `NOTIFIERTYPE` VARCHAR(255) BINARY NULL, PRIMARY KEY (`ID`) ) ENGINE=INNODB : Invalid default value for 'SEND_ON_SCM_FAILURE' com.mysql.jdbc.exceptions.MySQLSyntaxErrorException: Invalid default value for 'SEND_ON_SCM_FAILURE' 2.) With Derby, you'll be able to create your database but it fails when you try to upgrade from continuum 1.2.x to 1.3.x ERROR JPOX.RDBMS - Error thrown executing ALTER TABLE PROJECTNOTIFIER ADD SEND_ON_SCM_FAILURE CHAR(1) DEFAULT 'false' CHECK (SEND_ON_SCM_FAILURE IN ('Y','N')) : A truncation error was encountered trying to shrink CHAR 'false' to length 1. ERROR 22001: A truncation error was encountered trying to shrink CHAR 'false' to length 1.