You are welcome. The error means that there was no mattermost service configured in the first place to use systemd for starting and stopping the service.
I can confirm that the instance is up and running on my end too:
Moving back to the upgrade process, may I know how Mattermost was installed? Were you referring to the Installing Mattermost on Debian originally? Since step 5 in the upgrade documentation only highlights for Ubuntu and RHEL, I don’t think it applies in this case.
Also, what happens when you stop the Mattermost service from Plesk and proceed with the upgrade? Does it go through?
And no I didn’t try stop the service from Plesk. I was afraid of messing something up.
Should I try to proceed with the update instructions, skipping #5, and using Plesk to stop and restart the service?
As long as you have the Mattermost backup handy for roll backs, I’d say go for it.
If you have run into any issues along the way, capture the mattermost.log and the error that you are seeing on your end (console and UI). Roll back if necessary.
I think it went through. How do I check the version? In the mobile app it says the serve version is 5.25 but just wanted to make sure that was correct.
Log in to the desktop / web app. Click on the 3 line icon and open up About Mattermost. You should be able to confirm that it is upgraded properly. For example: