Hello, @kur
When you mentioned that it does not run with Ubuntu autostart, do you mean that it does not automatically start when the server gets rebooted based on sudo systemctl enable mattermost.service ? Can you share the output of running the same command as you can see from the example I have below?
ahmaddanial@mattermost:~$ sudo systemctl status mattermost.service
● mattermost.service - Mattermost
Loaded: loaded (/lib/systemd/system/mattermost.service; disabled; vendor preset: enabled)
Active: active (running) since Wed 2020-05-20 00:34:30 UTC; 1min 57s ago
Main PID: 16450 (mattermost)
Tasks: 12
Memory: 62.2M
CPU: 2.365s
CGroup: /system.slice/mattermost.service
└─16450 /opt/mattermost/bin/mattermost
May 20 00:34:30 mattermost mattermost[16450]: 2020-05-20T00:34:30.896Z info app/server.g
May 20 00:34:30 mattermost mattermost[16450]: 2020-05-20T00:34:30.897Z info app/server.g
May 20 00:34:30 mattermost mattermost[16450]: 2020-05-20T00:34:30.897Z info commands/ser
May 20 00:34:30 mattermost systemd[1]: Started Mattermost.
May 20 00:35:30 mattermost mattermost[16450]: 2020-05-20T00:35:30.813Z debug migrations/
May 20 00:35:30 mattermost mattermost[16450]: 2020-05-20T00:35:30.814Z debug migrations/
May 20 00:35:30 mattermost mattermost[16450]: 2020-05-20T00:35:30.819Z debug jobs/schedu
May 20 00:35:38 mattermost mattermost[16450]: 2020-05-20T00:35:38.944Z debug migrations/
May 20 00:35:39 mattermost mattermost[16450]: 2020-05-20T00:35:39.162Z info migrations/w
May 20 00:35:39 mattermost mattermost[16450]: 2020-05-20T00:35:39.163Z debug jobs/jobs.g
ahmaddanial@mattermost:~$ sudo systemctl enable mattermost.service
Created symlink from /etc/systemd/system/mysql.service.wants/mattermost.service to /lib/systemd/system/mattermost.service.
What happens when you try to start the service again using sudo systemctl restart mattermost.service since the status is showing Active: inactive (dead)?