 <p>(1) I always add this as you suggested</p> <pre><code>config.assets.initialize_on_precompile = false </code></pre> <p>(2) But also, if using ActiveAdmin and/or Devise, exclude their routes when precompiling assets by coding routes.rb as follows</p> <pre><code> unless ARGV.join.include?('assets:precompile') ActiveAdmin.routes(self) devise_for :admin_users, ...etc.... devise_for :users, ...etc... devise_scope :user do get "/login", ..etc end </code></pre> <p>as per <a href="https://github.com/gregbell/active_admin/issues/474" rel="nofollow">here</a> and elsewhere</p>