I’ve managed to get an error when I have the master as writeonly and a separate slave as readonly. But I still get a blank page when I set the master as read/write using the default.
Notice: Undefined variable: server in /var/www/html/wp-content/plugins/hyperdb/db.php on line 627
Fatal error: Call to undefined function mysql_error() in /var/www/html/wp-content/plugins/hyperdb/db.php on line 629