Open php.ini
vim /etc/php5/fpm/php.ini
Add following line.
session.save_path = "/var/run/php5/sessions"
Save and exit.
Run following commands.
mkdir -p /var/run/php5/sessions/
chown -R www-data:www-data /var/run/php5/
cp -rp /var/lib/php5/* /var/run/php5/sessions/
service php5-fpm restart
Edit cron on Debian/Ubuntu
vim /etc/cron.d/php5
Find 2 occurrences of /var/lib/php5/ and replace them with /var/run/php5/sessions/
This cronjob keeps deleting old sessions from time to time. If you forget to do this, you will get disk full error.
That’s it!