Cant access session CI 2.1.3 to subdomain CI 3.0.4

I cant access session data from "domain.com" to subdomain "sub.domain.com"
domain.com -> CI 2.1.3
sub.domain.com -> CI 3.0.4

I know that the version difference is causing this because when I tried CI 2.1.3 to CI 2.13 it worked. The $_SESSION is shared between the 2 application.

But I don't want to change any of our CI version

Is there any work around to share session between 2.1.3 and 3.0.4

Now it is only showing when I try print the session from my subdomain
Array ( [__ci_last_regenerate] => 1460446731)

And I noticed in the save path that my subdomain is saving its own session file

I hope someone could help me with this

Any input will be greatly appreciated. Thanks