Rails server not starting. Gems all installed, I'm confused - ruby-on-rails-3

Question

I went to restart my rails server today and when I went to fire it back up here's the error I got. I've tried everything and haven't been able to crack it. I uninstalled and reinstalled activesupport 3.1.0, and it seems like there's an error in activesupport itself, which I doubt I can fix. So, color me confused (paint me perplexed). Any advice much appreciated.
$ RESQUE_INTERFACE=true rails s
=> Booting WEBrick
=> Rails 3.1.0 application starting in development on http://0.0.0.0:3000
=> Call with -d to detach
=> Ctrl-C to shutdown server
Exiting
/Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:234:in `load': /Users/nickgoddard/codebase/newshop/config/initializers/session_store.rb:3: syntax error, unexpected ':', expecting $end (SyntaxError)
...sion_store :cookie_store, key: '_newshop_session'
^
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:234:in `load'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:223:in `load_dependency'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:640:in `new_constants_in'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:223:in `load_dependency'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:234:in `load'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/engine.rb:555
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/engine.rb:554:in `each'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/engine.rb:554
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/initializable.rb:25:in `instance_exec'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/initializable.rb:25:in `run'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/initializable.rb:50:in `run_initializers'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/initializable.rb:49:in `each'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/initializable.rb:49:in `run_initializers'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/application.rb:92:in `initialize!'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/railtie/configurable.rb:30:in `send'
from /Library/Ruby/Gems/1.8/gems/railties-3.1.0/lib/rails/railtie/configurable.rb:30:in `method_missing'
from /Users/nickgoddard/codebase/newshop/config/environment.rb:5
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:240:in `require'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:240:in `require'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:223:in `load_dependency'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:640:in `new_constants_in'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:223:in `load_dependency'
from /Library/Ruby/Gems/1.8/gems/activesupport-3.1.0/lib/active_support/dependencies.rb:240:in `require'
from /Users/nickgoddard/codebase/newshop/config.ru:4
from /Library/Ruby/Gems/1.8/gems/rack-1.3.6/lib/rack/builder.rb:51:in `instance_eval'
from /Library/Ruby/Gems/1.8/gems/rack-1.3.6/lib/rack/builder.rb:51:in `initialize'
from /Users/nickgoddard/codebase/newshop/config.ru:1:in `new'
from /Users/nickgoddard/codebase/newshop/config.ru:1

Answer 1

You're trying to run Ruby 1.9 code on Ruby 1.8, specifically the session_store hash parameters.
Usually, when you create a new Rails app, it should know this, but I'm not sure of the specifics about how you set up your app (or maybe you cloned someone else's?). To create an app and force it to use the 1.8 style of hashes, do:
rails new my_app --old-style-hash
Or, you can use something like rvm or rbenv to install Ruby 1.9 and use that instead.