Cloudron Error: Error getting IP of mail service after upgrade ubuntu 16.04 > 18

[youhost]

Hello, I have cloudron version 6.2.7 on 16.04 on kimsufi a dedicated server.
I've followed this guide to upgrade: https://docs.cloudron.io/guides/upgrade-ubuntu-18/
All is good and I'am successfully running Ubuntu 18.04.5 LTS.

But I have a problem with the maillserver: Error getting IP of mail service.
During the upgrade there was a request from the installer for reconfiguring Postfix. Even if I selected to keep the current configuration, I was ask by the installer to select a service (?), I've selected "internet website".
Then I was ask for the System mail name, I've set the hostname instead of my.mydomain.com.

Could this configuration be the cause of the error?

Thank you for your software and support,
Joseph

[nebulon]

@youhost not sure if this is related to the postfix configs, it sounds a bit more like maybe the local resolving does not work. Can you check if the unbound service is up and running?

[youhost]

@nebulon thank you, I've checked unbound and it seems to be properly running:

root@my:~# systemctl status unbound
● unbound.service - Unbound DNS Resolver
   Loaded: loaded (/etc/systemd/system/unbound.service; enabled; vendor preset
   Active: active (running) since Mon 2021-08-30 09:36:44 CEST; 1 day 4h ago
 Main PID: 803 (unbound)
    Tasks: 1 (limit: 4653)
   CGroup: /system.slice/unbound.service
           └─803 /usr/sbin/unbound -d

Do you have any other suggestion?
Should I try to Update Cloudron to 6.3.4?
Thanks

[nebulon]

@youhost it is probably faster if we can take a direct look at the system to avoid much back and forth. If you want to do so, please enable remote SSH support and send a mail with your dashboard domain to support@cloudron.io

Otherwise we need more context here, like where do you see the error you mentioned? System logs, app logs or service logs? Have you tried to restart the mail service using the dashboard?

[youhost]

thank you @nebulon , I've enabled SSH access and dropped you a support request directly from support form.

[nebulon]

This actually turned out to be a postfix issue, as @youhost already initially suspected.
So the mail container would not start, since postfix was running and hogging port 25. The solution in this case is to stop and disable postfix:

root@my:~# docker restart mail
Error response from daemon: Cannot restart container mail: driver failed programming external connectivity on endpoint mail (80745a182e99c96ca09dcb0a3775c919d7cd6907ba060410d860b2bd5929440e): Error starting userland proxy: listen tcp4 0.0.0.0:25: bind: address already in use
root@my:~# systemctl status postfix
● postfix.service - Postfix Mail Transport Agent
   Loaded: loaded (/lib/systemd/system/postfix.service; enabled; vendor preset: enabled)
   Active: active (exited) since Sun 2021-08-29 20:16:02 CEST; 2 days ago
 Main PID: 1654 (code=exited, status=0/SUCCESS)
    Tasks: 0 (limit: 4653)
   CGroup: /system.slice/postfix.service

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.
root@my:~# systemctl stop postfix && systemctl disable postfix
Synchronizing state of postfix.service with SysV service script with /lib/systemd/systemd-sysv-install.
Executing: /lib/systemd/systemd-sysv-install disable postfix
root@my:~# docker restart mail
mail
root@my:~#