When I compare my 'old' config.php with the new, I can only point out these differences at the end of the file...
My old config.php:
/* That's all, stop editing! Happy blogging. */
define('WP_POST_REVISIONS', false);
define('ABSPATH', dirname(__FILE__).'/');
require_once(ABSPATH.'wp-settings.php');
?>
The new one from 2.7:
/* That's all, stop editing! Happy blogging. */
/** WordPress absolute path to the WordPress directory. */
if ( !defined('ABSPATH') )
define('ABSPATH', dirname(__FILE__) . '/');
/** Sets up WordPress vars and included files. */
require_once(ABSPATH . 'wp-settings.php');
?>
Somehow WP gave me the message when trying to upgrade, that my username and password were ok, but that it could not find/connect the database and asked me of I had permission to do so.
Why isn't the new config.php not working for me? The rest of the content is the same.