Upgrading from 2.9.0.beta8 broke the site, unrecoverable

[JammyDodger]

There are also some good pointers on how to manually update from the server in this topic:

How do I manually update Discourse and Docker image to latest?

If you self-host Discourse, you occasionally need to run a manual update via the command line to get the latest security releases newest libraries. These updates are not picked up in admin/upgrade, which is why you’ll occasionally need to do this additional step. Discourse itself should be updated about twice a month, by clicking the “Update to Latest Version” button in your admin dashboard ( admin/upgrade). We do beta releases roughly once every week. Every two months we recommend SSH’ing…

A ./launcher rebuild app can often be a good Plan B, and if you get any errors during that you can scroll up and have a read.