ruby-on-rails – Ruby on rails：Heroku生产中不允许使用基本的

我做了一个简单的端点,在默认的ApplicationController中测试我可爱的Hello World.这是我的控制器：

ApplicationController的

class ApplicationController < ActionController::Base
  protect_from_forgery with: :exception
  def hello
    render html: "hello,world"
  end
end

它工作得非常好：

但是当我在Heroku中部署项目时,它返回的方法不允许.

任何想法我做错了什么？
这是我拥有的其他重要文件

的Gemfile

source 'https://rubygems.org'

gem 'rails','5.1.2'
gem 'puma','3.9.1'
gem 'sass-rails','5.0.6'
gem 'uglifier','3.2.0'
gem 'coffee-rails','4.2.2'
gem 'jquery-rails','4.3.1'
gem 'turbolinks','5.0.1'
gem 'jbuilder','2.7.0'

group :development,:test do
  gem 'sqlite3','1.3.13'
  gem 'byebug','9.0.6',platform: :mri
end

group :development do
  gem 'web-console','3.5.1'
  gem 'listen','3.0.8'
  gem 'spring','2.0.2'
  gem 'spring-watcher-listen','2.0.1'
end

group :production do
  gem 'pg','0.20.0'
end

# Windows does not include zoneinfo files,so bundle the tzinfo-data gem
gem 'tzinfo-data',platforms: [:mingw,:mswin,:x64_mingw,:jruby]

路线

Rails.application.routes.draw do
  # For details on the DSL available within this file,see http://guides.rubyonrails.org/routing.html
  root 'application#hello'
end

在我推到Heroku之前,我做了

> bundle update
> bundle install --without production