> Rails went on to release subsequent versions, each of which advocated doing a near rewrite of working code and obsoleted/broke many of the libraries in the ec

> Rails went on to release subsequent versions, each of which advocated doing a near rewrite of working code and obsoleted/broke many of the libraries in the ecosystem. As someone else said this isn't really correct. Since version 3 (released in 2010) the external API has been pretty much the same, bar a few minor breaking changes and new features. The internal APIs however have changed a lot. The issue I've had with upgrading since then hasn't been Rails, but third party libraries (gems) I also used. As it's not possible to make a method truly private in Ruby, they often hook into whatever they needed to work. They are then abandoned and aren't updated, and so if you are stuck relying on a certain library, you will have a hard time upgrading Rails. I also had a few cases of incompatibilities with Ruby versions (before 2.0 it didn't use semver), but thankfully that seems to be over now.