==== REQUIRED BASIC INFO OF YOUR IREDMAIL SERVER ====
- iRedMail version (check /etc/iredmail-release):  2024030401 (Backend: mariadb, Date: 2024-04-08 12:13:19) iRedMail Easy: https://www.iredmail.org/easy.html

- Deployed with iRedMail Easy
- Linux/BSD distribution name and version: Debian 10
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Nginx
- Manage mail accounts with iRedAdmin-Pro? yes
====

Note: all OS updates applied  (apt update & apt upgrade reports all up to date).

I just applied the latest iRedEasy update and since then dovecot is broken.
This started as soon as the update finished.  I've rebooted the server as well just in case.

Where do I look next ?

/var/log/dovecot/dovecot.log
-------------------------------
Apr  8 12:17:22 mail dovecot: log(32580): Warning: Killed with signal 15 (by pid=1 uid=0 code=kill)
Apr  8 12:17:22 mail dovecot: log(32580): Warning: Shutting down logging for 'imap-hibernate: ' with 1 clients
Apr  8 12:17:22 mail dovecot: log(32580): Warning: Shutting down logging for 'imap: ' with 1 clients
Apr  8 12:17:22 mail dovecot: log(32580): Warning: Shutting down logging for 'stats: ' with 1 clients
Apr  8 12:18:05 mail dovecot: lda: Fatal: Internal error occurred. Refer to server log for more information.
Apr  8 12:18:24 mail dovecot: lda: Fatal: Internal error occurred. Refer to server log for more information.
Apr  8 12:18:36 mail dovecot: lda: Fatal: Internal error occurred. Refer to server log for more information.