I have an app currently in Rails 3.2.21 running on Ruby 2.0.0. In short order, I need to get it running on Ruby 2.5.7. Can I do that without moving up from 3.2.21? (Please, no "you should be running on a more modern, supported Rails version; I know that, but that’s likely a much bigger project than moving to a newer Ruby version [if it will work with my current Rails version], and I will do that, but after the deadline).
And if the answer is “mostly, except for x, y, z”, any insight you can give as to what might not work would be appreciated.