Codeigniter sessions across sub domains

Question

I have multiple subdomains and i'm trying to use the sessions across subdomains.

http://example.com
http://subdomain.example.com

I have also set the cookie domain in config.php

$config['cookie_domain'] = ".example.com";

The session userdata and also flashdata are empty when used in the other domain. Im using the same session table as well for both CI instance

Answer 1

From the following solution : Sharing sessions

Both the cookie_domain and cookie prefix has to be set

$config['cookie_domain'] = ".example.com";
$config['cookie_prefix'] = "example_";