Just a heads-up for self-hosted stable branch users. For me the upgrade via the GUI failed, I’m not sure if this would happen to everyone, as I saw some errors about unicorn processes, which tends to be a random issue in my experience. But at any rate that left my forum in a state where it claimed to be up-to-date in /admin/update while still being stuck on the old version.
So I had to SSH into the server and /var/discourse/launcher rebuild app two times, the first time it just upgrades Postgres:
UPGRADE OF POSTGRES COMPLETE
Old 13 database is stored at /shared/postgres_data_old
To complete the upgrade, rebuild again using:
./launcher rebuild app
And the second time it finishes the rest of the upgrades.
After that was all over and verifying that my data was intact I also did a /var/discourse/launcher cleanup to get rid of the huge backup file that it created for the old database.