Rails: Webpacker 4.2 can't find application in /app/public/packs/manifest.json heroku
Solution 1
It looks like there's no application.css
in your manifest.json
which means you might not be importing any css from within your Webpack javascript files.
If that's all true, then you can fix the error in production by one of the following:
- Quick (temporary) fix: Add
extract_css: false
to yourproduction
block inconfig/webpacker.yml
(which would mimic your local environments) - If you don't want to compile css with Webpacker: Remove
<%= stylesheet_pack_tag 'application' %>
from your application layout - If you want to compile some css with Webpacker: Import at least one css file from your Webpack javascript
Solution 2
I was getting the same error on my local instance also.
After trying out a lot of workarounds, the following steps worked for me
bundle exec rails webpacker:install
Though this command was failing with the following error
gyp: No Xcode or CLT version detected! gyp ERR! configure error gyp ERR! stack Error:
gyp
failed with exit code: 1 gyp ERR! stack at ChildProcess.onCpExit (/Users//Documents/Ruby/udemy/test/alpha-blog/alpha-blog/node_modules/node-gyp/lib/configure.js:345:16) gyp ERR! stack at ChildProcess.emit (node:events:376:20) gyp ERR! stack at Process.ChildProcess._handle.onexit (node:internal/child_process:284:12) gyp ERR! System Darwin 19.6.0 gyp ERR! command "/usr/local/Cellar/node/15.5.0/bin/node" "/Users//Documents/Ruby/udemy/test/alpha-blog/alpha-blog/node_modules/node-gyp/bin/node-gyp.js" "rebuild" "--verbose" "--libsass_ext=" "--libsass_cflags=" "--libsass_ldflags=" "--libsass_library=" gyp ERR! cwd /Users/***/Documents/Ruby/udemy/test/alpha-blog/alpha-blog/node_modules/node-sass gyp ERR! node -v v15.5.0 gyp ERR! node-gyp -v v3.8.0 gyp ERR! not ok
To correct the issue I used the following stack overflow answer (on macOS catalina)
https://stackoverflow.com/a/60860951/5876113
Then I ran the following command
bundle exec rails webpacker:install
After doing above steps I didn't get the error again. Please verify if this works for you as you are facing the issue on Heroku deployment.
Solution 3
If you are using Rails 6+ with webpacker then due to the latest rails 6 update the both javascript and css files are moved under app/javascript
instead of app/assets
.
app/javascript:
├── packs:
│ # only webpack entry files here
│ └── application.js
└── src:
│ └── application.css
└── images:
└── logo.svg
But if you have upgraded from older version to new version but still want to compile CSS from app/assets/stylesheets
folder then follow the below tweaks:
- update the below in
config/webpacker.yml
for webpack to includeapp/assets
in the resolved path.
// config/webpacker.yml
resolved_paths: ['app/assets']
- copy below line to
app/javascript/packs/application.js
.
// app/javascript/packs/application.js
import 'stylesheets/application'
This should fix your CSS compilation issue when you run bin/webpack-dev-server
.
Solution 4
The accepted solution above resolves the issue for most but if like me you continued to have problems after following every instruction and every solution. The below might help you.
After going down a rabbit hole of errors, I found the following works.
In my experience, its to do with webpacker and your nvm installation. To try the solution, start by reverting any other actions you did to debug the issue. You need to ensure that you are running the latest webpacker version.
I would then run:
rails webpacker:compile
in your terminal.
If it compiles without a node warning then all good. if it gives you a warning about your node version, and or it does not compile, install the latest LTS node version. mine is 16.13.1. for ubuntu. . This is important. The latest version of node is not necessarily the latest lts version. You need to install in your home directory. Run:
nvm install --lts
nvm use --lts
You may want to set this as your default eg. :
nvm alias default 16.13.1
Also ensure that your application layout has:
<%= javascript_pack_tag 'application', 'data-turbolinks-track': 'reload' %>
Once that is done run webpacker compile again as above.
if you have any issues after this you can also try adding below in your config / initializer / assets.rb file:
Rails.application.config.assets.precompile += %w(application.js)
Justin
Updated on July 09, 2022Comments
-
Justin almost 2 years
I'm a bit stumped. My local rails app works great with webpacker 4.2 and react, but when deploying to production gives me the wonderful
can't find application in /app/public/packs/manifest.json
error.Here's what I've tried:
- Tried adding/removing turbo link details for javascript pack tag.
- Removed javascript include tag (not sure if this helps or not)
- Ensure I'm on the latest webpacker
4.2
- ran rake assets:clean && rake assets:precompile manually on heroku just to ensure things are getting built.
Am I missing a build step or something in production that would be causing this? What is left to check?
Server error:
2019-12-03T15:18:19.022024+00:00 app[web.1]: I, [2019-12-03T15:18:19.021952 #30] INFO -- : [aa0374eb-bab1-40cc-b40b-6ae3d195e07d] Completed 500 Internal Server Error in 112ms (ActiveRecord: 30.4ms | Allocations: 21296) 2019-12-03T15:18:19.023103+00:00 app[web.1]: F, [2019-12-03T15:18:19.023029 #30] FATAL -- : [aa0374eb-bab1-40cc-b40b-6ae3d195e07d] 2019-12-03T15:18:19.023107+00:00 app[web.1]: [aa0374eb-bab1-40cc-b40b-6ae3d195e07d] ActionView::Template::Error (Webpacker can't find application in /app/public/packs/manifest.json. Possible causes: 2019-12-03T15:18:19.023109+00:00 app[web.1]: 1. You want to set webpacker.yml value of compile to true for your environment 2019-12-03T15:18:19.023111+00:00 app[web.1]: unless you are using the `webpack -w` or the webpack-dev-server. 2019-12-03T15:18:19.023114+00:00 app[web.1]: 2. webpack has not yet re-run to reflect updates. 2019-12-03T15:18:19.023116+00:00 app[web.1]: 3. You have misconfigured Webpacker's config/webpacker.yml file. 2019-12-03T15:18:19.023118+00:00 app[web.1]: 4. Your webpack configuration is not creating a manifest. 2019-12-03T15:18:19.023120+00:00 app[web.1]: Your manifest contains: { "application.js": "/packs/js/application-2a0e2c932678ebbf2ae7.js", "application.js.map": "/packs/js/application-2a0e2c932678ebbf2ae7.js.map", "entrypoints": { "application": { "js": [ "/packs/js/application-2a0e2c932678ebbf2ae7.js" ], "js.map": [ "/packs/js/application-2a0e2c932678ebbf2ae7.js.map" ] }, "server_rendering": { "js": [ "/packs/js/server_rendering-eb794d024d4852e8ab55.js" ], "js.map": [ "/packs/js/server_rendering-eb794d024d4852e8ab55.js.map" ] } }, "server_rendering.js": "/packs/js/server_rendering-eb794d024d4852e8ab55.js", "server_rendering.js.map": "/packs/js/server_rendering-eb794d024d4852e8ab55.js.map" } ... <%= stylesheet_link_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %> <%= stylesheet_pack_tag 'application', media: 'all', 'data-turbolinks-track': 'reload' %> <%= javascript_pack_tag 'application' %> <link href="https://fonts.googleapis.com/css?family=Open+Sans|Roboto+Slab:700&display=swap" rel="stylesheet"> 2019-12-03T15:18:19.023193+00:00 app[web.1]: [aa0374eb-bab1-40cc-b40b-6ae3d195e07d] app/views/layouts/application.html.erb:10
Webpacker.yml
# Note: You must restart bin/webpack-dev-server for changes to take effect default: &default source_path: app/javascript source_entry_path: packs public_root_path: public public_output_path: packs cache_path: tmp/cache/webpacker check_yarn_integrity: false webpack_compile_output: false # Additional paths webpack should lookup modules # ['app/assets', 'engine/foo/app/assets'] resolved_paths: ['app/assets'] # Reload manifest.json on all requests so we reload latest compiled packs cache_manifest: false # Extract and emit a css file extract_css: false static_assets_extensions: - .jpg - .jpeg - .png - .gif - .tiff - .ico - .svg - .eot - .otf - .ttf - .woff - .woff2 extensions: - .jsx - .vue - .mjs - .js - .sass - .scss - .css - .module.sass - .module.scss - .module.css - .png - .svg - .gif - .jpeg - .jpg development: <<: *default compile: true # Verifies that correct packages and versions are installed by inspecting package.json, yarn.lock, and node_modules check_yarn_integrity: true # Reference: https://webpack.js.org/configuration/dev-server/ dev_server: https: false host: localhost port: 3035 public: localhost:3035 hmr: false # Inline should be set to true if using HMR inline: true overlay: true compress: true disable_host_check: true use_local_ip: false quiet: false headers: 'Access-Control-Allow-Origin': '*' watch_options: ignored: '**/node_modules/**' test: <<: *default compile: true # Compile test packs to a separate directory public_output_path: packs-test production: <<: *default # Production depends on precompilation of packs prior to booting for performance. compile: true # Extract and emit a css file extract_css: true # Cache manifest.json for performance cache_manifest: true