title: Rails server error after updating Ruby (Name Error)
body: <p>I updated Ruby to 2.2.2 from 2.0.0 because I think it may have been causing issues with Heroku, but now when I try and start the rails server I'm getting a name error, and because I'm new to RoR I have no idea what's causing it. </p>
  
  <p>Here is my log:  </p>
  
  <pre><code>C:\row\dev\my_app&gt;rails s
  C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionview-4.2.1/lib/action_view/helpers.
  rb:40:in `&lt;module:Helpers&gt;': uninitialized constant ActionView::Helpers::ActiveM
  odelHelper (NameError)
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionview-4.2.1/lib/action_
  view/helpers.rb:4:in `&lt;module:ActionView&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionview-4.2.1/lib/action_
  view/helpers.rb:3:in `&lt;top (required)&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionview-4.2.1/lib/action_
  view/base.rb:5:in `&lt;top (required)&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionview-4.2.1/lib/action_
  view/view_paths.rb:1:in `&lt;top (required)&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionpack-4.2.1/lib/abstrac
  t_controller/rendering.rb:4:in `&lt;top (required)&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionpack-4.2.1/lib/action_
  controller/base.rb:204:in `&lt;class:Base&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionpack-4.2.1/lib/action_
  controller/base.rb:164:in `&lt;module:ActionController&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/actionpack-4.2.1/lib/action_
  controller/base.rb:5:in `&lt;top (required)&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/responders-2.1.0/lib/respond
  ers/controller_method.rb:37:in `&lt;top (required)&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/responders-2.1.0/lib/respond
  ers.rb:15:in `&lt;module:Responders&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/responders-2.1.0/lib/respond
  ers.rb:9:in `&lt;top (required)&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/devise-3.5.1/lib/devise.rb:7
  :in `&lt;top (required)&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/bundler-1.10.5/lib/bundler/r
  untime.rb:76:in `require'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/bundler-1.10.5/lib/bundler/r
  untime.rb:76:in `block (2 levels) in require'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/bundler-1.10.5/lib/bundler/r
  untime.rb:72:in `each'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/bundler-1.10.5/lib/bundler/r
  untime.rb:72:in `block in require'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/bundler-1.10.5/lib/bundler/r
  untime.rb:61:in `each'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/bundler-1.10.5/lib/bundler/r
  untime.rb:61:in `require'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/bundler-1.10.5/lib/bundler.r
  b:134:in `require'
          from C:/row/dev/david_youtube/config/application.rb:7:in `&lt;top (required
  )&gt;'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/com
  mands/commands_tasks.rb:78:in `require'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/com
  mands/commands_tasks.rb:78:in `block in server'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/com
  mands/commands_tasks.rb:75:in `tap'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/com
  mands/commands_tasks.rb:75:in `server'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/com
  mands/commands_tasks.rb:39:in `run_command!'
          from C:/row/Ruby22/lib/ruby/gems/2.2.0/gems/railties-4.2.1/lib/rails/com
  mands.rb:17:in `&lt;top (required)&gt;'
          from bin/rails:4:in `require'
          from bin/rails:4:in `&lt;main&gt;'
  </code></pre>