==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):     0.9.9
- Deployed with iRedMail Easy or the downloadable installer? No
- Linux/BSD distribution name and version: Ubuntu LTS 16.04
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? Yes
- [IMPORTANT] Related original log or error message is required if you're experiencing an issue.
====

I get following error when cron job executes  /bin/bash /var/vmail/backup/backup_sogo.sh:

* Backup all users' data under /var/vmail/backup/sogo/2019/02/25
<0x0x25e15b0[SOGoCache]> Cache cleanup interval set every 300.000000 seconds
<0x0x25e15b0[SOGoCache]> Using host(s) '127.0.0.1' as server(s)
2019-02-25 04:01:01.657 sogo-tool[56425] user 'bilevskis' unknown
2019-02-25 04:01:01.665 sogo-tool[56425] user 'davids.birulis' unknown
2019-02-25 04:01:01.672 sogo-tool[56425] user 'emils' unknown
2019-02-25 04:01:01.683 sogo-tool[56425] user 'gunta.stebele' unknown
2019-02-25 04:01:01.729 sogo-tool[56425] user 'laura.bernita' unknown
2019-02-25 04:01:01.740 sogo-tool[56425] user 'majaslapa' unknown
2019-02-25 04:01:01.748 sogo-tool[56425] user 'meistars1' unknown
2019-02-25 04:01:01.757 sogo-tool[56425] user 'raimonds.grants' unknown
2019-02-25 04:01:01.780 sogo-tool[56425] user 'solveiga.petersone' unknown
2019-02-25 04:01:01.787 sogo-tool[56425] user 'valters.kalnins' unknown
* Compress backup files.
* Old backup found. Deleting: /var/vmail/backup/sogo/2018/11/27.tar.bz2.