RailsでJSON API用のバックエンドを作っていたら、ActiveAdminが 401を吐いた場合 ref: http://qiita.com/tsumekoara/items/48f0b6d1230d5d704c06

file0.txt

Started GET "/admin" for ::1 at 2015-05-12 18:06:23 +0900
Processing by Admin::DashboardController#index as HTML
Completed 401 Unauthorized in 0ms

file1.txt

  # ==> Navigation configuration
  # Lists the formats that should be treated as navigational. Formats like
  # :html, should redirect to the sign in page when the user does not have
  # access, but formats like :xml or :json, should return 401.
  #
  # If you have any extra navigational formats, like :iphone or :mobile, you
  # should add them to the navigational formats lists.
  #
  # The "*/*" below is required to match Internet Explorer requests.
  config.navigational_formats = ['*/*', :json]

file2.txt

  config.navigational_formats = ['*/*', :json, :html]