==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release): 1.0
- Deployed with iRedMail Easy or the downloadable installer? download
- Linux/BSD distribution name and version: CentOS 7
- 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 regularly see these errors. Any idea what might be causing it?

mysqldump: Got error: 1049: "Unknown database '...'" when selecting the database
mysqldump: Got error: 1049: "Unknown database '...'" when selecting the database
mysqldump: Got error: 1049: "Unknown database '...'" when selecting the database
mysqldump: Got error: 1049: "Unknown database '...'" when selecting the database
mysqldump: Got error: 1049: "Unknown database '...'" when selecting the database
mysqldump: Got error: 1049: "Unknown database '...'" when selecting the database ==> Backup completed successfully.
==> Detailed log (/var/vmail/backup/mysql/2020/01/28/2020.01.28.03.30.01.log):
=========================
* Starting backup: 2020.01.28.03.30.01.
* Backup directory: /var/vmail/backup/mysql/2020/01/28.
* Backing up databases ...
  - mysql [DONE]
  - vmail [DONE]
  - policyd [DONE]
  - amavisd [DONE]
  - roundcubemail [DONE]
  - iredadmin [DONE]
  - iredapd [DONE]
* File size:
----
4.0K    /var/vmail/backup/mysql/2020/01/28/amavisd-2020.01.28.03.30.01.sql.bz2
4.0K    /var/vmail/backup/mysql/2020/01/28/iredadmin-2020.01.28.03.30.01.sql.bz2
4.0K    /var/vmail/backup/mysql/2020/01/28/iredapd-2020.01.28.03.30.01.sql.bz2
4.0K    /var/vmail/backup/mysql/2020/01/28/mysql-2020.01.28.03.30.01.sql.bz2
4.0K    /var/vmail/backup/mysql/2020/01/28/roundcubemail-2020.01.28.03.30.01.sql.bz2
4.0K    /var/vmail/backup/mysql/2020/01/28/vmail-2020.01.28.03.30.01.sql.bz2
----
* Backup completed (Success? YES).