Next.js: Public assets with subPath don't work in production build

[marcin-piela-sf]

Bug report

Public assets with subPath don't work in production build

To Reproduce

1. npx create-next-app
2. Add next.config.js with content

module.exports = {
  basePath: '/test/sub-path',
  trailingSlash: false,
}

1. Edit file pages/index.js and replace line

<img src="/vercel.svg" alt="Vercel Logo" className={styles.logo} />

with

<img src="/test/sub-path/vercel.svg" alt="Vercel Logo" className={styles.logo} />

1. Run dev application npm run dev - everything works fine
2. Run prod application npm run build npm run start - static image asset doesn't work - 404

Expected behavior

Public assets should work in dev and prod

System information

• OS: macOs
• Version of Next.js: 9.5.3
• Version of Node.js: v13.14.0

[richardhomewood]

I am experiencing the exact same issue today on an identical system.

Interestingly, building a static site with next export does work, which leads me to believe it's the next server module itself where the bug lies.

[marcin-piela-sf]

Yes, and it works on 9.5.2 correctly

[marcin-piela-sf]

Any progress on it?

[colinhemphill]

This is also preventing us from upgrading past 9.5.2. I see that a PR was already opened, but I may take a crack at it if it will get us moving forward on this fix.

[ricardoGlobant]

Is there any workaround for this issue while the fix is ready?

[IkeLutra]

@ricardoGlobant I have worked around this by using the custom server setup of Next JS and using express static to serve those files. This is _ok_ but obviously comes with all the downsides of using a custom server.

https://nextjs.org/docs/advanced-features/custom-server
https://expressjs.com/en/starter/static-files.html