The db_version function is different for mysql/mysqli.. by one thing: 1.8 declares $matches = array(); before setting it.. that's it. Unless its comparing to a different value, it is exactly the same.Checked, it uses builtin php version_compare function to check that mysql is >= 5.0.. should be pretty straightforward.Are you getting any errors in the logs etc?If not, you could probably bypass this (if you KNOW its greater than 5.0), by simply returning true from: /include/class.setup.php line 97: function check_mysql_version() { return true;// (version_compare(db_version(), $this->getMySQLVersion())>=0); }