`require'：无法加载此类文件-cancan（LoadError）

Question

I'm using the CanCan gem with ActiveAdmin. It is working as expected in dev, but when pushed to a staging server I get the following error:

`require': cannot load such file -- cancan (LoadError)

In my case, this is caused by the 'require' line in ActiveAdmin's CanCan adapter.

I've searched Google for potential explanations but have come up empty-handed.

What might be the cause of such an error, and how can I go about fixing it?

Update:

Here is my config/initializers/active_admin.rb :

ActiveAdmin.setup do |config|
  config.authentication_method = :authenticate_user!
  config.authorization_adapter = ActiveAdmin::CanCanAdapter
  config.cancan_ability_class = "Ability"
  config.current_user_method = :current_user
  config.logout_link_path = :destroy_user_session_path
  config.allow_comments = false
  config.batch_actions = true
end

Answer 1

Restarting the entire machine fixed this.

I had tried restarting both nginx and unicorn, but I had yet to restart the machine itself. For whatever reason, this did the trick.

Thanks for your thoughts / suggestions.