Resolved Webmailer doesn't work anymore after having it disabled temporarily

[PeterKi]

Server operating system version

Ubuntu 22.04

Plesk version and microupdate number

Plesk Obsidian Web Admin Edition Version 18.0.58 Update #2

I have migrated my plesk server to a new host and after everything was up and running, I checked the horde webmailer for my domains.
The webmailers did work well.
On the Tools & Settings - Webmail Services it says:
"If you need to hide a webmail service temporarily, disable it using the button below."
Unluckily, I did try it and disabled Horde but after re-enabling it, the webmailer page doesn't open anymore.
Instead, I get a default page as attached.
Mail - Mail Settings show that the Mail Service and Horde Webmail is enabled for all my 2 domains.
The DNS record for webmail.[myDomain] show a proper setup.
How can I get the webmailer working again?

 

[PeterKi]

Additional Info:
I already did a server reboot and I temporarily set the Webmailer to NONE in Mail - Mail Settings for my domains but nothing of it solved the problem.

 

[Peter Debik]

It needs at least the server restart interval set in Tools & Settings > Apache. Instead, you can restart Nginx and Apache manually, e.g.

# apachectl -t
# systemctl reload apache2
# nginx -t
# systemctl reload nginx

If this does not help, try to examine the configuration files in /var/www/vhosts/system/<domain name>/conf whether the webmail subdomain is configured in them. If not, reconfigure the web server configuration files.

 

[PeterKi]

Thanks for the quick reply.
# apachectl -t
Syntax OK
# systemctl reload apache2.service
# nginx -t
nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
nginx: configuration file /etc/nginx/nginx.conf test is successful
# systemctl reload nginx

# find /var/www/vhosts/system/*/conf | grep -i -e horde -e webmail

no output from the last command.
Does Horde possibly require a special PHP Version?
Maybe it helps if I uninstall/re-install the webmail module?

 

[PeterKi]

I found the solution
Although Mail - Mail Settings did show the Mail Service as ON (see image), I clicked the Activate/Deactivate Services Button and set Mail Service and Webmail to enabled.
Now it works again.
To me, this seems to be a bug in the Plesk GUI.