uninitialized constant YAML (NameError)

[adavia]

I was following the exact same steps as mentioned in the docs but im getting this error when i restart my rails server

Exiting
/home/adavia/.rvm/gems/ruby-2.2.1/gems/private_pub-1.0.3/lib/private_pub.rb:21:in load_config': uninitialized constant YAML (NameError) from /home/adavia/.rvm/gems/ruby-2.2.1/gems/private_pub-1.0.3/lib/private_pub/engine.rb:8:inblock in class:Engine'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/initializable.rb:30:in instance_exec' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/initializable.rb:30:inrun'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/initializable.rb:55:in block in run_initializers' from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:226:inblock in tsort_each'
from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:348:in block (2 levels) in each_strongly_connected_component' from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:429:ineach_strongly_connected_component_from'
from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:347:in block in each_strongly_connected_component' from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:345:ineach'
from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:345:in call' from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:345:ineach_strongly_connected_component'
from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:224:in tsort_each' from /home/adavia/.rvm/rubies/ruby-2.2.1/lib/ruby/2.2.0/tsort.rb:203:intsort_each'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/initializable.rb:54:in run_initializers' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/application.rb:352:ininitialize!'
from /home/adavia/rails/social_chat/config/environment.rb:5:in <top (required)>' from /home/adavia/rails/social_chat/config.ru:3:inrequire'
from /home/adavia/rails/social_chat/config.ru:3:in block in <main>' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/rack-1.6.1/lib/rack/builder.rb:55:ininstance_eval'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/rack-1.6.1/lib/rack/builder.rb:55:in initialize' from /home/adavia/rails/social_chat/config.ru:innew'
from /home/adavia/rails/social_chat/config.ru:in <main>' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/rack-1.6.1/lib/rack/builder.rb:49:ineval'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/rack-1.6.1/lib/rack/builder.rb:49:in new_from_string' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/rack-1.6.1/lib/rack/builder.rb:40:inparse_file'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/rack-1.6.1/lib/rack/server.rb:299:in build_app_and_options_from_config' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/rack-1.6.1/lib/rack/server.rb:208:inapp'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/commands/server.rb:61:in app' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/rack-1.6.1/lib/rack/server.rb:336:inwrapped_app'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/commands/server.rb:139:in log_to_stdout' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/commands/server.rb:78:instart'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:80:in block in server' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:75:intap'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:75:in server' from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/commands/commands_tasks.rb:39:inrun_command!'
from /home/adavia/.rvm/gems/ruby-2.2.1/gems/railties-4.2.1/lib/rails/commands.rb:17:in <top (required)>' from bin/rails:4:inrequire'
from bin/rails:4:in `

'

[shyam916]

I am also facing the same issue. Did you find out the problem?

[adavia]

Yes. In your config/application.rb add require 'yaml'

[Li-Kevin]

I just met the same error as i run
$ rake db:migrate
and solved it by following your instruction, insert
require 'yaml'
in the config/application.rb file. Thanks a lot!

[horatiorosa]

Brilliant. adding require 'yaml' to the config/application.rb file worked perfectly.

[ghost]

Thank you, require 'yaml' in application.rb worked for me too. As I'm just learning Ruby, this has helped me so very much.