Greetings,
I have a client running Jenkins 2.346 on ubuntu 20.04 LTS running in a docker container.
They are wanting to upgrade to version 2.504 LTS.
How should I proceed, are there breaking change between releases?
I note the release notes have some commentary concerning change in each release.
What is the concensus on big bang vs incremental updates?
Cheers
GP
Hello and welcome to the community, @WeePecky! 
I’m not sure we have a consensus on this topic. You’ll likely find a mix here—some of us are all for jumping into the newest LTS, while others prefer gradual changes.
@mwp565733 has a back-of-the-napkin guide for upgrading that you might find helpful.
Personally, I’d start a new set of Docker containers with the latest LTS, check which plugins from the old controller are still necessary, install those on the new controller, update everything, and then import the jobs. But everyone’s experience can differ, so your mileage may vary!
Cheers!