we have been using Zammad (current: 3.1.x) on our own server under Debian for years. Since there used to be a problem with an update, we have been reluctant to update for years.
Now we finally want to dare! Are there things that need to be considered when making a version jump like this?
I updated debian first from 9 to 10 and the to 11, straight from 3.1 to 5.4.
No issues except resetting the cache (see updating) Updating Zammad — Zammad documentation