Webpacker can't find application

Robin Des Bois picture Robin Des Bois · Oct 7, 2019 · Viewed 18.2k times · Source

I'm creating a new rails application according to "Getting Started with Rails". The application starts normally in step 4.1. But when i create my first controller, i have a webpack error.

I'm new in webpack, i have red all documentation, but i don't understand what is wrong or missing...

  • Windows 10 1903
  • ruby 2.6
  • rails 6.0.0
  • nodeJS 12.11.0

rails webpacker:install
   identical  config/webpacker.yml
Copying webpack core config
       exist  config/webpack
   identical  config/webpack/development.js
   identical  config/webpack/environment.js
   identical  config/webpack/production.js
   identical  config/webpack/test.js
Copying postcss.config.js to app root directory
   identical  postcss.config.js
Copying babel.config.js to app root directory
   identical  babel.config.js
Copying .browserslistrc to app root directory
   identical  .browserslistrc
The JavaScript app source directory already exists
       apply  C:/Ruby26-x64/lib/ruby/gems/2.6.0/gems/webpacker-4.0.7/lib/install/binstubs.rb
  Copying binstubs
       exist    bin
   identical    bin/webpack
   identical    bin/webpack-dev-server
      append  .gitignore
Installing all JavaScript dependencies [4.0.7]
         run  yarn add @rails/webpacker from "."
yarn add v1.17.3
[1/4] Resolving packages...
[2/4] Fetching packages...
info [email protected]: The platform "win32" is incompatible with this module.
info "[email protected]" is an optional dependency and failed compatibility check. Excluding it from installation.
[3/4] Linking dependencies...
warning " > [email protected]" has unmet peer dependency "webpack@^4.0.0".
warning "webpack-dev-server > [email protected]" has unmet peer dependency "webpack@^4.0.0".
[4/4] Building fresh packages...
success Saved 1 new dependency.
info Direct dependencies
└─ @rails/[email protected]
info All dependencies
└─ @rails/[email protected]
Done in 4.48s.
Installing dev server for live reloading
         run  yarn add --dev webpack-dev-server from "."
yarn add v1.17.3
[1/4] Resolving packages...
[2/4] Fetching packages...
info [email protected]: The platform "win32" is incompatible with this module.
info "[email protected]" is an optional dependency and failed compatibility check. Excluding it from installation.
[3/4] Linking dependencies...
warning "webpack-dev-server > [email protected]" has unmet peer dependency "webpack@^4.0.0".
warning " > [email protected]" has unmet peer dependency "webpack@^4.0.0".
[4/4] Building fresh packages...
success Saved 1 new dependency.
info Direct dependencies
└─ [email protected]
info All dependencies
└─ [email protected]
Done in 4.92s.
Webpacker successfully installed �🎉🍰🍰

Webpacker::Manifest::MissingEntryError in Welcome#index

Showing C:/Users/[...]/site_test/app/views/layouts/application.html.erb where line #9 raised:

Webpacker can't find application in C:/Users/[...]/site_test/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.
Your manifest contains:
{
}

Extracted source (around line #9):

7
8      <%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %>
9      <%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>
10 </head>
11 <body>
12

Answer

dandeto picture dandeto · Oct 14, 2019

This error seems to be the key.

Your manifest contains:
{
}

Try simply running the yarn command in your project directory. That should result in a manifest.json file being created - among other things.

If that doesn't work, I found this issue on github from which I am verbatim reciting the following commands that may help you. This will reset all built assets and node_modules.

rm -rf node_modules
rails assets:clobber
yarn
rails assets:precompile

Check out that link for more information.