The first error is telling you that another instance of Ghost is running on port 2368. This is set in production.config.json and may be set using the ghost config --port 2368 option. Are you running more than one instance of Ghost? If not, then something else may have gone awry.
The other messages relate to systemd. This can be set using ghost config --process systemd.
After making any changes, you should run ghost restart.
Something definitely strange going on. The site has been running with no issues for years (with regular updates when required), and now these errors are appearing.
What’s strange is that when I ssh into the server and run:
cd /var/www/ghost
ghost ls
It tells me that no instances of Ghost are running… even though the site is live and working.
I’m going to attempt the config --process systemd command shortly, just running a backup.