Simple Rails App: Error Cannot visit Integer

The version of Ruby you're using (2.4.1) is not compatible with the version of Rails you're using (3.2.22.5). That version of Ruby requires at least Rails 5. Try downgrading to Ruby 2.3 or lower. You can use a Ruby version manager (i.e. rvm, rbenv or chruby) to control which Ruby is used when launching your application.

Edit

Just noticed you're already using rbenv from your stack trace. Add a .ruby-version file to your application's directory containing the following line:

2.3.4

Once you re-enter that directory, confirm the version via:

$> ruby -v
ruby 2.3.4p301 (2017-03-30 revision 58214) [x86_64-darwin16]

(or similar version) before launching rails.

I got this error yesterday and created a workaround which should make it work with ruby 2.4 and rails 3.2.

The commit that I got the idea from is at: https://github.com/rails/arel/commit/dc85a6e9c74942945ad696f5da4d82490a85b865

Just include the following in your rails initializers.

module Arel
  module Visitors
    class DepthFirst < Arel::Visitors::Visitor
      alias :visit_Integer :terminal
    end

    class Dot < Arel::Visitors::Visitor
      alias :visit_Integer :visit_String
    end

    class ToSql < Arel::Visitors::Visitor
      alias :visit_Integer :literal
    end
  end
end

For future Googlers. I had the same problem but I needed to apply a variant of Thomas Dziedzic solution.

I have ruby 2.5.1 and rails 4.2.10 running in my system.

As shown in this commit ToSql was changed from Arel::Visitors::Visitorto Arel::Visitors::Reduce

So this is my updated solution. In a rails initializer put this:

module Arel
  module Visitors
    class DepthFirst < Arel::Visitors::Visitor
      alias :visit_Integer :terminal
    end

    class Dot < Arel::Visitors::Visitor
      alias :visit_Integer :visit_String
    end

    class ToSql < Arel::Visitors::Reduce
      alias :visit_Integer :literal
    end
  end
end