Rails error when starting server

Question

I'm just starting with rails and I'm having the following error when starting the server.

$ rails s
/usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/tracelines19.rb:12:in `require': dlopen(/usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/trace_nums19.bundle, 9): Symbol not found: _ruby_current_thread (LoadError)
Referenced from: /usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/trace_nums19.bundle
Expected in: flat namespace in /usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/trace_nums19.bundle - /usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/trace_nums19.bundle
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/tracelines19.rb:12:in `rescue in <module:TraceLineNumbers>'
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/tracelines19.rb:8:in `<module:TraceLineNumbers>'
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/tracelines19.rb:6:in `<top (required)>'
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/linecache19.rb:69:in `require'
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/linecache19-0.5.12/lib/linecache19.rb:69:in `<top (required)>'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/runtime.rb:68:in `require'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/runtime.rb:68:in `block (2 levels) in require'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/runtime.rb:66:in `each'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/runtime.rb:66:in `block in require'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/runtime.rb:55:in `each'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler/runtime.rb:55:in `require'
from /usr/local/rvm/gems/ruby-1.9.3-p194@global/gems/bundler-1.1.5/lib/bundler.rb:119:in `require'
from /Users/Crysfel/Sites/rails/quizzpot/config/application.rb:13:in `<top (required)>'
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.8/lib/rails/commands.rb:53:in `require'
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.8/lib/rails/commands.rb:53:in `block in <top (required)>'
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.8/lib/rails/commands.rb:50:in `tap'
from /usr/local/rvm/gems/ruby-1.9.3-p194/gems/railties-3.2.8/lib/rails/commands.rb:50:in `<top (required)>'
from script/rails:6:in `require'
from script/rails:6:in `<main>'

I'm using:

Rails 3.2.8 ruby 1.9.3p194

Here's my config/application.rb file:

    require File.expand_path('../boot', __FILE__)

    # Pick the frameworks you want:
    require "active_record/railtie"
    require "action_controller/railtie"
    require "action_mailer/railtie"
    require "active_resource/railtie"
    require "sprockets/railtie"
    # require "rails/test_unit/railtie"

    if defined?(Bundler)
      # If you precompile assets before deploying to production, use this line
      Bundler.require(*Rails.groups(:assets => %w(development test)))
      # If you want your assets lazily compiled in production, use this line
      # Bundler.require(:default, :assets, Rails.env)
    end

    module Quizzpot
      class Application < Rails::Application
    # Settings in config/environments/* take precedence over those specified here.
    # Application configuration should go into files in config/initializers
    # -- all .rb files in that directory are automatically loaded.

    # Custom directories with classes and modules you want to be autoloadable.
    # config.autoload_paths += %W(#{config.root}/extras)

    # Only load the plugins named here, in the order given (default is alphabetical).
    # :all can be used as a placeholder for all plugins not explicitly named.
    # config.plugins = [ :exception_notification, :ssl_requirement, :all ]

    # Activate observers that should always be running.
    # config.active_record.observers = :cacher, :garbage_collector, :forum_observer

    # Set Time.zone default to the specified zone and make Active Record auto-convert to this zone.
    # Run "rake -D time" for a list of tasks for finding time zone names. Default is UTC.
    # config.time_zone = 'Central Time (US & Canada)'

    # The default locale is :en and all translations from config/locales/*.rb,yml are auto loaded.
    # config.i18n.load_path += Dir[Rails.root.join('my', 'locales', '*.{rb,yml}').to_s]
    # config.i18n.default_locale = :de

    # Configure the default encoding used in templates for Ruby 1.9.
    config.encoding = "utf-8"

    # Configure sensitive parameters which will be filtered from the log file.
    config.filter_parameters += [:password]

    # Use SQL instead of Active Record's schema dumper when creating the database.
    # This is necessary if your schema can't be completely dumped by the schema dumper,
    # like if you have constraints or database-specific column types
    # config.active_record.schema_format = :sql

    # Enforce whitelist mode for mass assignment.
    # This will create an empty whitelist of attributes available for mass-assignment for all models
    # in your app. As such, your models will need to explicitly whitelist or blacklist accessible
    # parameters by using an attr_accessible or attr_protected declaration.
    # config.active_record.whitelist_attributes = true

    # Enable the asset pipeline
    config.assets.enabled = true

    # Version of your assets, change this if you want to expire all your assets
    config.assets.version = '1.0'
  end
end

Answer 1

The stack trace shows you are having a problem with the linecache19 gem. A Google search shows that others have encountered the same problem: it seems to be an incompatibility between that gem and Ruby 1.9.3.

Is linecache19 in your Gemfile? If so, can you just remove it? (Do you really need it?) If it's not in the Gemfile, look in Gemfile.lock and see if it's listed as a dependency of one of your other gems.