Hi I''ve been following this issue on Lighthouse (https:// rails.lighthouseapp.com/projects/8994-ruby-on-rails/tickets/1977- actioncontrollercachingsweeper-autoloading-is-broken). I''ve since upgraded to 2-3-stable which contain''s Josh''s fix, but I''m still seeing the same error: `load_missing_constant'': uninitialized constant ActionController::Caching::Sweeper (NameError) I''ve tried a variety of fixes as suggested in the Lighthouse comments, all to no avail. The only way I can get my app to start is by replacing: @@@ class MySweeper < ActionController::Caching::Sweeper @@@ with @@@ require ''rails/actionpack/lib/action_controller/caching/sweeper'' class MySweeper < ActionController::Caching::Sweeping::Sweeper @@@ This is clearly wrong. Can anyone help? My environment.rb file is as follows, if this helps? Rails::Initializer.run do |config| %w(sweepers observers accounting).each do |dir| config.load_paths << "#{RAILS_ROOT}/app/#{dir}" end config.cache_store = :file_store, "#{RAILS_ROOT}/tmp/cache" config.active_record.observers = :my_sweeper config.active_record.default_timezone = :utc config.action_controller.session_store = :active_record_store config.action_mailer.default_charset = "utf-8" end