Ruby on rails server not starting: bundler-1.14.6 `require': cannot load such file

Upgrading and old Ruby on rails app from ruby 1.9.3-p545 to ruby 2.3.1. on development server. Rails 3.2.8 will be upgraded to 4.2.8 (not done yet).

RVM and ruby version upgraded to 2.3.1, bundle installed successfully.

The following error occurs when running development server:

/home/javier/.rvm/gems/ruby-2.3.1/gems/activesupport-3.2.8/lib/active_support/values/time_zone.rb:270: warning: circular argument reference - now
/home/javier/.rvm/gems/ruby-2.3.1/gems/bundler-1.14.6/lib/bundler/runtime.rb:91:in `require': cannot load such file -- zip/zip (LoadError)
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/bundler-1.14.6/lib/bundler/runtime.rb:91:in `block (2 levels) in require'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/bundler-1.14.6/lib/bundler/runtime.rb:86:in `each'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/bundler-1.14.6/lib/bundler/runtime.rb:86:in `block in require'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/bundler-1.14.6/lib/bundler/runtime.rb:75:in `each'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/bundler-1.14.6/lib/bundler/runtime.rb:75:in `require'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/bundler-1.14.6/lib/bundler.rb:107:in `require'
    from /home/javier/Workspace/e-nrg/config/application.rb:7:in `<top (required)>'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/railties-3.2.8/lib/rails/commands.rb:53:in `require'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/railties-3.2.8/lib/rails/commands.rb:53:in `block in <top (required)>'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/railties-3.2.8/lib/rails/commands.rb:50:in `tap'
    from /home/javier/.rvm/gems/ruby-2.3.1/gems/railties-3.2.8/lib/rails/commands.rb:50:in `<top (required)>'
    from script/rails:6:in `require'
    from script/rails:6:in `<main>'