ruby on rails - RoR Application built using spree works fine in local not in heroku -

i have ror application thats year old uses older versions of multiple spree dependencies have ensured works , expected without dependency issues in local ubuntu mysql database. when push heroku not getting errors while pushing. when load application on browser getting application error.

when run heroku logs get. not sure causing app crash on heroku. can give me insight possibly happening.

2013-07-31t15:33:04.533860+00:00 app[web.1]:  2013-07-31t15:33:24.224146+00:00 app[web.1]: => booting webrick 2013-07-31t15:33:24.224146+00:00 app[web.1]: => rails 3.1.4 application starting in production on http://0.0.0.0:30818 2013-07-31t15:33:24.224146+00:00 app[web.1]: => call -d detach 2013-07-31t15:33:24.224146+00:00 app[web.1]: => ctrl-c shutdown server 2013-07-31t15:33:24.224146+00:00 app[web.1]: exiting 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/bundler/gems/spree_email_to_friend-f38187568f33/app/mailers/spree/to_friend_mailer.rb:1:in `<top (required)>' 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/polyglot-0.3.3/lib/polyglot.rb:63:in `require' 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:240:in `block in require' 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:225:in `load_dependency' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/config/environment.rb:5:in `<top (required)>' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:240:in `require' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/rack-1.3.10/lib/rack/builder.rb:40:in `parse_file' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/initializable.rb:55:in `block in run_initializers' 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/polyglot-0.3.3/lib/polyglot.rb:63:in `require' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/application.rb:96:in `initialize!' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/railtie/configurable.rb:30:in `method_missing' 2013-07-31t15:33:24.225435+00:00 app[web.1]: /app/vendor/bundle/ruby/1.9.1/bundler/gems/spree_email_to_friend-f38187568f33/app/mailers/spree/to_friend_mailer.rb:2:in `<class:tofriendmailer>': undefined method `preferred_mails_from' nil:nilclass (nomethoderror) 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:240:in `require' 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:348:in `require_or_load' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/commands.rb:54:in `block in <top (required)>' 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:302:in `depend_on' 2013-07-31t15:33:24.225435+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:214:in `require_dependency' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/polyglot-0.3.3/lib/polyglot.rb:63:in `require' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/initializable.rb:54:in `each' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:223:in `load_dependency' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/polyglot-0.3.3/lib/polyglot.rb:63:in `require' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/engine.rb:417:in `block (2 levels) in eager_load!' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/engine.rb:416:in `each' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/engine.rb:416:in `block in eager_load!' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/engine.rb:414:in `each' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/rack-1.3.10/lib/rack/builder.rb:51:in `initialize' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:240:in `block in require' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/rack-1.3.10/lib/rack/server.rb:254:in `start' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/commands/server.rb:70:in `start' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/rack-1.3.10/lib/rack/builder.rb:51:in `instance_eval' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/engine.rb:414:in `eager_load!' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/application/railties.rb:8:in `each' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/application/railties.rb:8:in `all' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/engine.rb:412:in `eager_load!' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/rack-1.3.10/lib/rack/server.rb:200:in `app' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/rack-1.3.10/lib/rack/server.rb:304:in `wrapped_app' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/commands.rb:49:in `<top (required)>' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/commands/server.rb:46:in `app' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/application/finisher.rb:51:in `block in <module:finisher>' 2013-07-31t15:33:24.225644+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/initializable.rb:30:in `instance_exec' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/initializable.rb:30:in `run' 2013-07-31t15:33:24.225801+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/initializable.rb:54:in `run_initializers' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    script/rails:6:in `require' 2013-07-31t15:33:24.226708+00:00 app[web.1]:    script/rails:6:in `<main>' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:223:in `block in load_dependency' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/activesupport-3.1.4/lib/active_support/dependencies.rb:640:in `new_constants_in' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/config.ru:3:in `block in <main>' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/config.ru:in `new' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/config.ru:in `<main>' 2013-07-31t15:33:24.226233+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/rack-1.3.10/lib/rack/builder.rb:40:in `eval' 2013-07-31t15:33:24.226392+00:00 app[web.1]:    /app/vendor/bundle/ruby/1.9.1/gems/railties-3.1.4/lib/rails/commands.rb:49:in `tap' 2013-07-31t15:33:26.428134+00:00 heroku[web.1]: process exited status 1 2013-07-31t15:33:26.442115+00:00 heroku[web.1]: state changed starting crashed 2013-07-31t15:33:27.208422+00:00 heroku[router]: at=error code=h10 desc="app crashed" method=get path=/ host=ird.herokuapp.com fwd="115.160.227.226" dyno= connect= service= status=503 bytes= 2013-07-31t15:33:27.645038+00:00 heroku[router]: at=error code=h10 desc="app crashed" method=get path=/favicon.ico host=ird.herokuapp.com fwd="115.160.227.226" dyno= connect= service= status=503 bytes=