After updating phpmyadmin I always get this error 🙂 This seems to be an issue with Nginx server not Apache ones.
Cannot start session without errors, please check errors given in your PHP and/or webserver log file and configure your PHP installation properly.
To fix it just change the owner of this folder
/var/lib/php/session
To Nginx 🙂 because by default it always does it to apache, which sucks 🙂