share login/logout sessions across two installs?

I’m having some issues sharing the user sessions across two installs.

(a) site on http://stolenmx.com
(b) site on http://arcade.stolenmx.com

I have installed B in the same database as A and I have defined the user and user_meta tables so I am sharing user data and users etc but I can’t seem to bridge the sessions.

I have tried using cookies a few different ways but nothing works.

This is what I’m using in (b) wp-config at the moment with no effect,

define('COOKIE_DOMAIN', 'www.stolenmx.com');
define('COOKIEPATH', "https://wordpress.stackexchange.com/");     

does anyone know how to get this working?

I’m actually using UserPro on site (a) to manage registration and login and I have wp-login.php disabled. Could this be why cookie isn’t working cause UserPro saves the cookie elsewhere or just simply doesn’t use one?

You also need to define a matching COOKIEHASH for both sites – a random 32 bit string will do.

By default, COOKIEHASH is an MD5 hash of the site URL, and is used to generate the default names for all authentication-related cookies. Hence why, at the moment, your cross-domain login isn’t working (the names of the cookies aren’t consistent, as COOKIEHASH will be different for each site).

See wp_cookie_constants() for more information.

So to recap, your wp-config.php for both sites should look like:

define( 'COOKIE_DOMAIN', '.stolenmx.com' ); // Dot prefix
define( 'COOKIEPATH',    "https://wordpress.stackexchange.com/" );
define( 'COOKIEHASH',    md5( 'stolenmx.com' ) );

define( 'CUSTOM_USER_TABLE',      'wp_users' );
define( 'CUSTOM_USER_META_TABLE', 'wp_usermeta' );