cannot load such file -- rack/respond_to (LoadError)

[ravindra9278]

I have successfully installed gem but I don't know why its is giving error.

cannot load such file -- rack/respond_to (LoadError) /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:inrequire' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in block in require' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:238:inblock in load_dependency' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:647:in new_constants_in' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:238:inload_dependency' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:274:in require' /var/www/sites/preitv10/releases/ror-cms/lib/email_preference.rb:2:in<top (required)>' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:457:in load' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:457:inblock in load_file' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:647:in new_constants_in' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:456:inload_file' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:354:in require_or_load' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:494:inload_missing_constant' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:184:in const_missing' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/inflector/methods.rb:261:inconst_get' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/inflector/methods.rb:261:in block in constantize' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/inflector/methods.rb:259:ineach' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/inflector/methods.rb:259:in inject' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/inflector/methods.rb:259:inconstantize' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/activesupport-4.2.6/lib/active_support/dependencies.rb:566:in get' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/actionpack-4.2.6/lib/action_dispatch/middleware/stack.rb:24:inklass' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/actionpack-4.2.6/lib/action_dispatch/middleware/stack.rb:43:in build' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/actionpack-4.2.6/lib/action_dispatch/middleware/stack.rb:118:inblock in build' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/actionpack-4.2.6/lib/action_dispatch/middleware/stack.rb:118:in each' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/actionpack-4.2.6/lib/action_dispatch/middleware/stack.rb:118:ininject' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/actionpack-4.2.6/lib/action_dispatch/middleware/stack.rb:118:in build' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/railties-4.2.6/lib/rails/engine.rb:502:inapp' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/railties-4.2.6/lib/rails/application/finisher.rb:34:in block in <module:Finisher>' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/railties-4.2.6/lib/rails/initializable.rb:30:ininstance_exec' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/railties-4.2.6/lib/rails/initializable.rb:30:in run' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/railties-4.2.6/lib/rails/initializable.rb:55:inblock in run_initializers' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:226:in block in tsort_each' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:348:inblock (2 levels) in each_strongly_connected_component' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:429:in each_strongly_connected_component_from' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:347:inblock in each_strongly_connected_component' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:345:in each' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:345:incall' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:345:in each_strongly_connected_component' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:224:intsort_each' /home/daffolap-198/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:203:in tsort_each' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/railties-4.2.6/lib/rails/initializable.rb:54:inrun_initializers' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/railties-4.2.6/lib/rails/application.rb:352:in initialize!' /var/www/sites/preitv10/releases/ror-cms/config/environment.rb:5:in<top (required)>' config.ru:3:in require' config.ru:3:inblock in

' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/rack-1.6.4/lib/rack/builder.rb:55:in instance_eval' /home/daffolap-198/.rvm/gems/ruby-2.2.1@ror_cms/gems/rack-1.6.4/lib/rack/builder.rb:55:ininitialize' config.ru:1:in new' config.ru:1:in

' /var/lib/gems/1.9.1/gems/passenger-5.0.23/src/helper-scripts/rack-preloader.rb:110:in eval' /var/lib/gems/1.9.1/gems/passenger-5.0.23/src/helper-scripts/rack-preloader.rb:110:inpreload_app' /var/lib/gems/1.9.1/gems/passenger-5.0.23/src/helper-scripts/rack-preloader.rb:156:in <module:App>' /var/lib/gems/1.9.1/gems/passenger-5.0.23/src/helper-scripts/rack-preloader.rb:30:inmodule:PhusionPassenger' /var/lib/gems/1.9.1/gems/passenger-5.0.23/src/helper-scripts/rack-preloader.rb:29:in <main>'