Rails s error: `method_missing': undefined method `active_record'

Question

My rails project works before. I got this error because I deleted mysql and everything associated mysql.

Then I reinstalled mysql. It got this error. Then I reinstalled ruby and rails. The error is still here. Using "rails new myapp", then "bundle instal", then "rails s",

I got the following error:

=> Booting WEBrick
=> Rails 4.0.2 application starting in development on 

=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
Exiting
**/home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/railtie/configuration.rb:95:in `method_missing': undefined method `active_record' for #<Rails::Application::Configuration:0x0000000303cae8> (NoMethodError)
    from /home/cwu/Dropbox/project/web/atop/config/environments/development.rb:23:in `block in <top (required)>'**
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/railtie/configurable.rb:24:in `class_eval'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/railtie/configurable.rb:24:in `configure'
    from /home/cwu/Dropbox/project/web/atop/config/environments/development.rb:1:in `<top (required)>'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/activesupport-4.0.2/lib/active_support/dependencies.rb:229:in `require'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/activesupport-4.0.2/lib/active_support/dependencies.rb:229:in `block in require'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/activesupport-4.0.2/lib/active_support/dependencies.rb:214:in `load_dependency'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/activesupport-4.0.2/lib/active_support/dependencies.rb:229:in `require'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/engine.rb:591:in `block (2 levels) in <class:Engine>'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/engine.rb:590:in `each'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/engine.rb:590:in `block in <class:Engine>'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:30:in `instance_exec'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:30:in `run'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:55:in `block in run_initializers'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:226:in `block in tsort_each'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:348:in `block (2 levels) in each_strongly_connected_component'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:418:in `block (2 levels) in each_strongly_connected_component_from'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:427:in `each_strongly_connected_component_from'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:417:in `block in each_strongly_connected_component_from'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:44:in `each'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:44:in `tsort_each_child'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:411:in `call'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:411:in `each_strongly_connected_component_from'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:347:in `block in each_strongly_connected_component'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `each'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `call'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:345:in `each_strongly_connected_component'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:224:in `tsort_each'
    from /home/cwu/.rvm/rubies/ruby-2.1.0/lib/ruby/2.1.0/tsort.rb:205:in `tsort_each'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/initializable.rb:54:in `run_initializers'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/application.rb:215:in `initialize!'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/railtie/configurable.rb:30:in `method_missing'
    from /home/cwu/Dropbox/project/web/atop/config/environment.rb:5:in `<top (required)>'
    from /home/cwu/Dropbox/project/web/atop/config.ru:3:in `require'
    from /home/cwu/Dropbox/project/web/atop/config.ru:3:in `block in <main>'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `instance_eval'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:55:in `initialize'
    from /home/cwu/Dropbox/project/web/atop/config.ru:in `new'
    from /home/cwu/Dropbox/project/web/atop/config.ru:in `<main>'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `eval'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:49:in `new_from_string'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/rack-1.5.2/lib/rack/builder.rb:40:in `parse_file'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/rack-1.5.2/lib/rack/server.rb:277:in `build_app_and_options_from_config'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/rack-1.5.2/lib/rack/server.rb:199:in `app'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/commands/server.rb:48:in `app'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/rack-1.5.2/lib/rack/server.rb:314:in `wrapped_app'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/commands/server.rb:75:in `start'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/commands.rb:76:in `block in <top (required)>'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/commands.rb:71:in `tap'
    from /home/cwu/.rvm/gems/ruby-2.1.0/gems/railties-4.0.2/lib/rails/commands.rb:71:in `<top (required)>'
    from bin/rails:4:in `require'
    from bin/rails:4:in `<main>'

Answer 1

Comment config.active_record.raise_in_transactional_callbacks = true in config/application.rb and config.active_record.migration_error = :page_load in config/environments/development.rb.

Answer 2

As a general fix, remove all references to active_record. Easiest way is to do a find on the root directory of "active_records", find all usages, and remove them. I found usages in config/application.rb and config/environments/development and production.rb.

Answer 3

Leedy Liu is right to some degree, but if you're getting this error when you create a new Rails app, t suggests a deeper problem with your environment

According to this answer, you may have require "active_record/railtie" commented out in your application.rb file. Please check to make sure this is not the case

You may have to re-install Rails with ActiveRecord to ensure the functionality is restored with your app. Have you tried this:

gem install bundler
gem install rails
bundle install

Other than that, you need to ensure Ruby on Rails is installed correctly. What env are you running? Linux or Windows?

Answer 4

Try:

    'gem install bundler'

then: 'bundle install' again.

See if it clears up.

Answer 5

The error is clear that in config/environments/development.rb:23 you configure active_record which is not loaded.

Just remove

config.active_record.migration_error = :page_load

Will be ok.