Ispconfig3 mailserver is not available after updating it from ubuntu 16.04 to ubuntu 18.04

Hi Community,
I wonder if you could help me solving my problem. I have a multiserver setup with Ispconfig 3.1.15p3. I have three different servers, one is for web and database, one is for email and one is for dns. UI is deployed onto webserver. I did a system upgrade on mail server from ubuntu 16.04 to ubuntu 18.04. Webserver and dnsserver are still ubuntu 16.04. The system upgrade was successful, but I can see some strange behavior.
After the update I can not create any new email account. I can fill all the required fields, but the changes are not geting populated to all servers. Here is the error message:

Code:

The following changes are not yet populated to all servers:
- Create email user: 1
- Create spam filter settings: 1

What I have checked so far:

• the new entries are added to mysql database on webserver that runs UI
• the new entries are NOT added to mailserver's mysql database
• the UI mysql server can be reached from mailserver with the already created username and password, and the newly created entries can be seen.
• on the UI I can see some error message for mailserver, such as SMTP Server is stopped, POP-3 server is stopped, IMAP server is stopped and mysql-Server is stopped (sorry if it is not exact, I had to translate back to English). These errors are strange for me, as checking the services indivudaly from the mailserver, they up and running, although, postfix is in active(exited) stage but dovecot and mysql are active (running) stage.
• emails can be sent and received by the email server

I assume something must be around the upgrade, but I have run out of ideas. Any help would be highly appreciated.

 

Thanks, that is a useful link. It turned out that the system purged php during the upgrade. I fixed it, but one error still exists, which is ui shows that the services (SMTP, POP3, IMAP, MySql) are down on mailserver. Is there any documentation about how the check is done? The services are running, there is no problem with them.

 

Hi @till , thank you for your answer. Could you please give me more clarification about the tests? The server runs the UI is another server than the mailserver. What do you mean by listening on localhost? The mailserver checks if the postfix, dovecot, mysql are running on its localhost, then reports the state to the other server that runs UI, or the UI server keep polling somehow the mailserver's services?