版本

• ruby 2.6.5p114 (2019-10-01 revision 67812) [x64-mingw32]
• Rails 6.0.4.1
• 数据库使用的 docker

# 
rails new react-app  --webpack=react --database=postgresql

# 
rails g controller pages index

我在路由页面 设置

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

报错显示

Webpacker can't find hello_react in C:/Users/18026/Desktop/react_rails_app/public/packs/manifest.json. Possible causes:
1. You want to set webpacker.yml value of compile to true for your environment
   unless you are using the `webpack -w` or the webpack-dev-server.
2. webpack has not yet re-run to reflect updates.
3. You have misconfigured Webpacker's config/webpacker.yml file.
4. Your webpack configuration is not creating a manifest.

解决方案：

1. 我尝试搜索答案，但是试了各种方案，没有解决 https://stackoverflow.com/questions/58270161/webpacker-cant-find-application 搜索无果