TypeError (no _dump_data is defined for class Mutex):
  activesupport (3.2.13) lib/active_support/message_verifier.rb:53:in `dump'
  activesupport (3.2.13) lib/active_support/message_verifier.rb:53:in `generate'
  actionpack (3.2.13) lib/action_dispatch/middleware/cookies.rb:300:in `[]='
  actionpack (3.2.13) lib/action_dispatch/middleware/session/cookie_store.rb:64:in `set_cookie'
  rack (1.4.5) lib/rack/session/abstract/id.rb:335:in `commit_session'
  rack (1.4.5) lib/rack/session/abstract/id.rb:211:in `context'
  rack (1.4.5) lib/rack/session/abstract/id.rb:205:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/cookies.rb:341:in `call'
  activerecord (3.2.13) lib/active_record/query_cache.rb:64:in `call'
  activerecord (3.2.13) lib/active_record/connection_adapters/abstract/connection_pool.rb:479:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/callbacks.rb:28:in `block in call'
  activesupport (3.2.13) lib/active_support/callbacks.rb:405:in `_run__3254096077457663663__call__2614245297655554673__callbacks'
  activesupport (3.2.13) lib/active_support/callbacks.rb:405:in `__run_callback'
  activesupport (3.2.13) lib/active_support/callbacks.rb:385:in `_run_call_callbacks'
  activesupport (3.2.13) lib/active_support/callbacks.rb:81:in `run_callbacks'
  actionpack (3.2.13) lib/action_dispatch/middleware/callbacks.rb:27:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/reloader.rb:65:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/remote_ip.rb:31:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/debug_exceptions.rb:16:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/show_exceptions.rb:56:in `call'
  railties (3.2.13) lib/rails/rack/logger.rb:32:in `call_app'
  railties (3.2.13) lib/rails/rack/logger.rb:16:in `block in call'
  activesupport (3.2.13) lib/active_support/tagged_logging.rb:22:in `tagged'
  railties (3.2.13) lib/rails/rack/logger.rb:16:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/request_id.rb:22:in `call'
  rack (1.4.5) lib/rack/methodoverride.rb:21:in `call'
  rack (1.4.5) lib/rack/runtime.rb:17:in `call'
  activesupport (3.2.13) lib/active_support/cache/strategy/local_cache.rb:72:in `call'
  rack (1.4.5) lib/rack/lock.rb:15:in `call'
  actionpack (3.2.13) lib/action_dispatch/middleware/static.rb:63:in `call'
  railties (3.2.13) lib/rails/engine.rb:479:in `call'
  railties (3.2.13) lib/rails/application.rb:223:in `call'
  rack (1.4.5) lib/rack/content_length.rb:14:in `call'
  railties (3.2.13) lib/rails/rack/log_tailer.rb:17:in `call'
  rack (1.4.5) lib/rack/handler/webrick.rb:59:in `service'
  /Users/ABroman/.rvm/rubies/ruby-1.9.3-p429/lib/ruby/1.9.1/webrick/httpserver.rb:138:in `service'
  /Users/ABroman/.rvm/rubies/ruby-1.9.3-p429/lib/ruby/1.9.1/webrick/httpserver.rb:94:in `run'
  /Users/ABroman/.rvm/rubies/ruby-1.9.3-p429/lib/ruby/1.9.1/webrick/server.rb:191:in `block in start_thread'