I&#x27;ve done the work before to make rails 3.2 work on 2.2. I recall the problem is due to a breaking Bcrypt name change and Yaml serialization, and it&#x27;s a one line patch. The maintainers are aware of the issue but held back so as to not break every 3.2 installation on a minor upgrade (would have to be called Rails 3.3 for semver?). Rails 4.0 isnt that hard of an upgrade path if you include the attraccessible gem.