Share WordPress Login Cookies Between Two Subdomain Installs

Question

I have two wordpress installs each on their own sub domain.

sub1.domain.com and sub2.domain.com

I want to share the login information between sub1 and sub2. I already have configured them to use the same MySQL database, and they use the same database table.

I am able to log in on both websites with the same credentials.

Sub2's wp-config.php file has the following code:

define('CUSTOM_USER_TABLE', 'wp_c_users');

define('CUSTOM_USERMETA_TABLE', 'wp_c_usermeta');

This all works great. My problem, is that the cookies are not being shared between the sites. Instead of sharing the cookies both sites just delete the others and create a new cookie.

I added the following code to both sub1 and sub2's wp-config.php:

define('COOKIEPATH','domain.com/'); // Replace with your initial domain name
define('SITECOOKIEPATH','domain.com/'); // Replace with your initial domain name
define( 'COOKIEHASH',    md5( 'Y@^ET#UF!RG7#KQXP04^WF' ) );
define('COOKIE_DOMAIN', 'domain.com');

When a user logs in to sub1, the cookie is created just fine, then when I go to sub2.domain.com, I am not also logged in on this site.

When I then try to log in to sub2.domain.com, it deletes sub1's cookies and overwrites them.

How can I get these two wordpress installations to use the same cookie instead of overwriting eachothers??

Any help much appreciated!

Answer 1

Today, I've posted a working solution for exactly the same problem. You can see it here: How to share WordPress session and cookies between domain and subdomain?. I use this method on several of my own websites.

Answer 2

Seems like you need to add a leading dot in the COOKIE_DOMAIN and just leave the COOKIEPATH and SITECOOKIEPATH undefined.

So the constants would be

define( 'COOKIEHASH', md5( 'Y@^ET#UF!RG7#KQXP04^WF' ) );
define( 'COOKIE_DOMAIN', '.domain.com' );