undefined method `action_mailer' with Ruby 1.9.2 and Rails 3.0.8

The full error is:

/Users/me/.rvm/gems/ruby-1.9.2-p180/gems/railties-3.0.8/lib/rails/railtie/configuration.rb:77:in `method_missing': undefined method `action_mailer' for #<Rails::Application::Configuration:0x00000开发者_如何转开发102f545f8> (NoMethodError)

I've searched several variations of this error and come up empty.

Thanks.

Probably you're requiring only specific parts from rails in you application.rb (i.e., not using require rails/all). Try putting require "rails/all" in there.

i uninstalled rails 3.0.8 files and then reinstalled rails 3.0.8 and that fixed the problem.