tail -f /var/log/roundcubemail/errors.log
[02-Jan-2020 17:38:37 UTC] PHP Warning: strtotime(): Invalid date.timezone value ‘IST’, we selected the timezone ‘UTC’ for now. in /usr/share/roundcubemail/program/lib/Roundcube/session/db.php on line 109
vi /etc/php.ini
date.timezone = "Asia/Kolkata"