If you happen to come across the following deprecation warning:
DEPRECATION WARNING: Giving :session_key to SessionStore is deprecated, please use :key instead. (called from new at /Users/dshimy/.rvm/gems/ruby-1.8.7-p249/gems/actionpack-2.3.8/lib/action_controller/middleware_stack.rb:72)
Take a look at your config/environment.rb file for the following:
config.action_controller.session = { :secret_key => '_sample_session', :secret => '00000000000000000000' }
and change it to:
config.action_controller.session = { :key => '_sample_session', :secret => '00000000000000000000' }
Thanks for posting this, you just saved me from a trip down the rabbit hole!
May be :session_key change to :key ?
Thanks! It also helped me. :)