I had the same error.
But I have to delete this line:
define('COOKIE_DOMAIN', '');
So just add this:
define('ADMIN_COOKIE_PATH', '/');
define('COOKIEPATH', '');
define(‘COOKIE_DOMAIN’, $_SERVER[‘HTTP_HOST’]);
And change this:
define( 'SUBDOMAIN_INSTALL', false );
(it was “true” before)
But hey, now I have my multisite working, THANKS TO THIS POST.
THANK YOU SO MUCH.