In my experience, upgrading rails used to be messy (e.g. 2->3 was a blood bath) but recent version upgrades have been mostly straightforward. It does help to s

In my experience, upgrading rails used to be messy (e.g. 2->3 was a blood bath) but recent version upgrades have been mostly straightforward. It does help to stay on top of gen upgrades as much as possible, but I do not believe this is a rails specific thing. Maybe useful: there are companies providing long term support for old rails versions.