Deploying to Heroku: Command "webpack" not found

[dwayne26 (Gerand McDowell)]

When I try to deploy to Heroku, I receive this error. Command "webpack" not found. I’ve tried solutions like looking into yarn and installing a package.json in the root. I’m not completely sure but I feel the problem could lie in my package.json needing additional information regarding ‘webpack’.

here is the error in the console:

Rails version :6.0.3.2

Ruby version : 2.7.1

[kmitov (Kiril Mitov)]

I remember I was fighting with this, but can not remember now how I resolved it. What is your build pack?

[soulchild]

Try add a nodeJS buildpack (make sure it is above Ruby buildpack) in Heroku dashboard -> your app -> Settings -> Buildpack

[s0kil (Daniel Sokil)]

Has anyone managed to solve this? I’m having a similar issue locally, yarn install is successful, but webpack is not found when starting rails server.

[jakehockey10 (Jake Smith)]

I’m having this same issue still. I’ve tried adding the build packs, I’ve tried without them. I’ve tried moving dependencies from devDependencies, no dice there either. When I run heroku run bash, and run which webpack, I get nothing. I’m seeing this issue all over github, but no solutions seem to exist that work for everyone.

[dwayne26 (Gerand McDowell)]

Hey, I never resolved the issue, just had to recreate the app, copy all the code and try redeploying it. It worked out the second time.

[Wobbles]

Just thought I’d document what worked for me here.

in package.json

...
  "dependencies": {
    ...
    "@rails/webpacker": "5.1.1",
    ...
  },
...
  "engines": {
    "node": "14.X"
  }
...

I changed my heroku config with this

heroku config:set NPM_CONFIG_PRODUCTION=false YARN_PRODUCTION=false

apparently that keeps some dependencies around for a little longer so that rails can do its thing.

Then I ran into the problem you had. So I added the heroku/nodejs build pack to the build packs as per @soulchild above. (Thanks @soulchild !)

[pebneter]

These three tips solved the issues for me (upgrading from Rails 5.2.4.5):

• package.json must contain web packer (see @Wobbles example)
• Make sure the build packs are configured
• Run “yarn” locally to update yarn.lock