THis is regarding the free plugin https://wordpress.org/plugins/wordpress-social-login/
it appears to me that hybridauth uses its on storage for sessiondata and probably gets the path from php session path but when you are using memcached it is a ip:port not a path.
I would really like to get memcached working but have been unable to find any help on the internet.
I get session variable not found error with the social login.
I am using wpfc + w3tc config