title: Migrating to Rails 3.2 - Undefined method 'session=' for ActionController::Base:Class
body: <p>I migrated an old Ruby (1.8.7) and Rails (2.2.2) application to Ruby (1.9.3) and Rails (3.2.12) following all of these excellent references:</p>
  
  <p><a href="http://github.com/rails/rails_upgrade.git" rel="nofollow">Rails Upgrade Script</a><br />
  <a href="http://blog.wolfman.com/articles/2010/12/17/upgrading-a-rails-2-dot-2-2-app-to-rails-3" rel="nofollow">Rails 3 Migration Blog</a><br />
  <a href="http://gregmoreno.wordpress.com/2010/08/11/rails-3-upgrade-part-1-booting-the-application/" rel="nofollow">Booting the Rails 3 App</a><br /> </p>
  
  <p>I am able to start up the app's Rails server but when I access the app via the browser, and then BLAMMO! I get a server error:</p>
  
  <p><strong>!! Unexpected error while processing request: undefined method `session=' for ActionController::Base:Class</strong></p>
  
  <p>When I grep -r for "session =" I get:</p>
  
  <pre><code>/var/www/vendor_sandbox/config/application.rb:    config.action_controller.session = {
  /var/www/vendor_sandbox/config/environment.rb.rails2:  config.action_controller.session = {
  /var/www/vendor_sandbox/destroy/config/environment.rb:  config.action_controller.session = {
  /var/www/vendor_sandbox/generate/config/environment.rb:  config.action_controller.session = {
  </code></pre>
  
  <p>According to a Google search for that error, it's an old issue from Rails 2 so I'm wondering If I missed something in the migration process or if this is something else. Thanks</p>
  
  <p>Here is my terminal session activity:</p>
  
  <pre><code>root@partners:/var/www/vendor_sandbox# ruby -v
  ruby 1.9.3p385 (2013-02-06 revision 39114) [i686-linux]
  root@partners:/var/www/vendor_sandbox# rails --version
  Rails 3.2.12
  root@partners:/var/www/vendor_sandbox# rails s
  =&gt; Booting Thin
  =&gt; Rails 3.2.12 application starting in development on     http://0.0.0.0:3000
  =&gt; Call with -d to detach
  =&gt; Ctrl-C to shutdown server
  
  &gt;&gt; Thin web server (v1.5.0 codename Knife)
  &gt;&gt; Maximum connections set to 1024
  &gt;&gt; Listening on 0.0.0.0:3000, CTRL+C to stop
  </code></pre>
  
  <p><strong>Then, I hit the application from a browser and:</strong></p>
  
  <pre><code>!! Unexpected error while processing request: undefined method `session=' for ActionController::Base:Class
  </code></pre>