==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 0.9.9
- Deployed with iRedMail Easy or the downloadable installer? Downloadable
- Linux/BSD distribution name and version: Ubuntu 18.04 LTS
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MariaDB
- Web server (Apache or Nginx): nginx
- Manage mail accounts with iRedAdmin-Pro? No
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I got the following log errors today:

/etc/cron.daily/logrotate:
Job for rsyslog.service failed.
See "systemctl status rsyslog.service" and "journalctl -xe" for details.
error: error running non-shared postrotate script for /var/log/php-fpm/php-fpm.log of '/var/log/php-fpm/*.log '
Job for rsyslog.service failed.
See "systemctl status rsyslog.service" and "journalctl -xe" for details.
error: error running non-shared postrotate script for /var/log/php-fpm/slow.log of '/var/log/php-fpm/*.log '
run-parts: /etc/cron.daily/logrotate exited with return code 1

Any idea how to fix it?