Devise::MissingWarden in Home#show Devise could not find the
Warden::Proxy instance on your request environment. Make sure that
your application is loading Devise and Warden as expected and that the
Warden::Manager middleware is present in your middleware stack. If
you are seeing this on one of your tests,ensure that your tests are
either executing the Rails middleware stack or that your tests are
using the Devise::Test::ControllerHelpers module to inject the
request.env['warden'] object for you.

这是我的控制器：

class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception

  private
  # Overwriting the sign_out redirect path method
  def after_sign_out_path_for(resource_or_scope)
    build_path
  end
end

这是我的两个部分观点：

<!-- views/devise/menu/_login_items.html.erb -->
<% if user_signed_in? %>
  <li>
  <%= link_to('logout',destroy_user_session_path,:method => :delete) %>
  </li>
<% else %>
  <li>
  <%= link_to('Login',new_user_session_path)  %>
  </li>
<% end %>

和

<!-- views/devise/menu/_registration_items.html.erb -->
<% if user_signed_in? %>
  <li>
  <%= link_to('Edit registration',edit_user_registration_path) %>
  </li>
<% else %>
  <li>
  <%= link_to('Register',new_user_registration_path)  %>
  </li>
<% end %>

调试之后,我发现问题来自我的“show”控制器中的这一行：template = HomeController.render(‘layouts / _template’)

谢谢你的帮助.