I'm upgrading YouTrack from 2020.3 to the latest version 2021.4. I've already upgraded Hub from the same old version to the latest version 2021.1. That works.
The problem I'm having is configuring YouTrack to use my Hub, it keeps giving me the error "Unknown host in Hub URL."
My Hub works, it's running and I can visit it.
I've tried several different URL's in the configuration for hub, with the /hub, without. With the port it's running on 1111 (it's behind an Nginx proxy) and without. Nothing seems to work but it used to, so what changed?
Is YouTrack trying to ping Hub on a specific port I may have blocked?
An "Unknown host" error must be a DNS issue.
YouTrack backend needs to connect to Hub backend, so make sure Hub URL is resolvable from where YouTrack is deployed.