Couldn't parse YAML at line 7 - RefineryCMS / Rails Issue

Question

Please could someone help me understand what has gone wrong, and how I can lookout/debug these things in the future. I have set-up a RefineryCMS app in Rails, worked on it, uploaded it to Heroku and have had both the local and remote copies working fine. After a period of about a month I return to the local copy to work on it, but it won't load. I can't understand why as nothing has changed. I tried deleting the local copy and cloning again from heroku but same issue exists. The error code is below when I try and create a rails server locally to run the app.

I would welcome help with the error, and perhaps how to spot/avoid these things in the future

 /home/adam/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych.rb:148:in `parse': couldn't parse YAML at line 7 column 0 (Psych::SyntaxError)
from /home/adam/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych.rb:148:in `parse_stream'
from /home/adam/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych.rb:119:in `parse'
from /home/adam/.rvm/rubies/ruby-1.9.2-p290/lib/ruby/1.9.1/psych.rb:106:in `load'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activerecord-3.0.11/lib/active_record/base.rb:1868:in `object_from_yaml'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activerecord-3.0.11/lib/active_record/attribute_methods/read.rb:129:in `unserialize_attribute'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activerecord-3.0.11/lib/active_record/attribute_methods/read.rb:112:in `_read_attribute'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activerecord-3.0.11/lib/active_record/attribute_methods/read.rb:101:in `read_attribute'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activerecord-3.0.11/lib/active_record/base.rb:1525:in `[]'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:158:in `value'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:61:in `block in to_cache'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:58:in `collect'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:58:in `to_cache'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:73:in `rewrite_cache'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:36:in `ensure_cache_exists!'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:44:in `cache_read'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:109:in `get'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-settings-1.0.9/app/models/refinery_setting.rb:95:in `find_or_set'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-images-1.0.9/lib/refinerycms-images.rb:33:in `block (2 levels) in <class:Engine>'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/dragonfly-0.9.8/lib/dragonfly/configurable.rb:35:in `configure'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/dragonfly-0.9.8/lib/dragonfly/configurable.rb:42:in `configure_with'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/refinerycms-images-1.0.9/lib/refinerycms-images.rb:24:in `block in <class:Engine>'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/initializable.rb:25:in `instance_exec'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/initializable.rb:25:in `run'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/initializable.rb:50:in `block in run_initializers'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/initializable.rb:49:in `each'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/initializable.rb:49:in `run_initializers'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/application.rb:134:in `initialize!'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/application.rb:77:in `method_missing'
from /home/adam/web/beloved/config/environment.rb:5:in `<top (required)>'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activesupport-3.0.11/lib/active_support/dependencies.rb:239:in `require'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activesupport-3.0.11/lib/active_support/dependencies.rb:239:in `block in require'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activesupport-3.0.11/lib/active_support/dependencies.rb:225:in `block in load_dependency'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activesupport-3.0.11/lib/active_support/dependencies.rb:593:in `new_constants_in'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activesupport-3.0.11/lib/active_support/dependencies.rb:225:in `load_dependency'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/activesupport-3.0.11/lib/active_support/dependencies.rb:239:in `require'
from /home/adam/web/beloved/config.ru:3:in `block in <main>'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/rack-1.2.4/lib/rack/builder.rb:46:in `instance_eval'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/rack-1.2.4/lib/rack/builder.rb:46:in `initialize'
from /home/adam/web/beloved/config.ru:1:in `new'
from /home/adam/web/beloved/config.ru:1:in `<main>'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/rack-1.2.4/lib/rack/builder.rb:35:in `eval'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/rack-1.2.4/lib/rack/builder.rb:35:in `parse_file'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/rack-1.2.4/lib/rack/server.rb:162:in `app'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/rack-1.2.4/lib/rack/server.rb:253:in `wrapped_app'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/rack-1.2.4/lib/rack/server.rb:204:in `start'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/commands/server.rb:65:in `start'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/commands.rb:30:in `block in <top (required)>'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/commands.rb:27:in `tap'
from /home/adam/.rvm/gems/ruby-1.9.2-p290@beloved2/gems/railties-3.0.11/lib/rails/commands.rb:27:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'

Thanks for your help, Adam

Answer 1

Add to config/boot.rb:

require 'yaml'
YAML::ENGINE.yamler = 'syck'

Read more here