You’ve updated Discourse, which means you need to now fix docker.
dist-upgrade could achieve this. Assuming you have copies of your backups and this is the only app on the server there’s little risk at this point. Worst case you will just need to re-run through the 30 minute install guide and restore a backup.
Was it you who built the server? Do you recall how it was built if so? The more information you can give us here, the quicker we can find you a solution.