knagaitsev / webpack-issue-repro

Adapted from the minimum reproducible test repo found here: webpack/webpack-dev-server#1514

Steps

Run the app

// start the backend server on port 8080
npm run server

// start webpack dev server on port 9000
npm run hot

Update the source to test HMR

Change the background-color in main.css

Issue 1 - publicPath

• Go to http://localhost:9000
• Change main.css
• See a 404 from http://localhost:9000/08a64a5d1bd954786070.hot-update.json
• The correct place to request from should be http://localhost:9000/dist/08a64a5d1bd954786070.hot-update.json

publicPath: '/dist/' from devServer is causing a 404 because it is not overriding publicPath of webpack.

• Uncomment the publicPath in webpack config output and it will work without a 404

This confirms: webpack/webpack-dev-server#1785

Issue 2 - Incorrect Port

• Uncomment the publicPath in webpack config output
• Go to http://localhost:8080
• Change main.css
• See a 404 from http://localhost:8080/dist/08a64a5d1bd954786070.hot-update.json
• The correct place to request from should be http://localhost:9000/dist/08a64a5d1bd954786070.hot-update.json

The port is evidently being inferred from window.location.port, when it should not be.

Conclusion

I think that a combination of these two issues are causing the problem here: webpack/webpack-dev-server#1385