Can't resolve 'xyz' with turbopack

[Kumneger0]

Module not found: Can't resolve 'fs'

1 | var fs = require('fs')
| ^^^^^^^^^^^^^
2 | var polyfills = require('./polyfills.js')
3 | var legacy = require('./legacy-streams.js')
4 | var clone = require('./clone.js')

i have got the same issue with webpack too, but i fixed that by using the following next config

const nextConfig: NextConfig = {
	webpack: (config, { isServer }) => {
  	if (isServer) {
  		return config;
  	}
  	config.resolve.fallback = { fs: false, net: false } // don't try to import this on the client
  	return config;
  }
 }
 

how can we tell turbopack to do exact same thing ?

[icyJoseph]

So like, here the issue is that you got away with it on webpack. Away with what? Importing server side code into the client.

I know that, often this can be out of your control, you need a util, or whatever from a library out of your control, and simply importing it into your client code, indirectly imports fs or any other Node.js module, but it is important to try and keep these separate.

Anyway, you can try this:

import type { NextConfig } from "next";

const nextConfig: NextConfig = {
  /* config options here */
  turbopack: {
    resolveAlias: {
      'fs': {
        browser: './src/lib/empty.ts'
      }
    }
  }
};

export default nextConfig;

Then I have a src/lib/empty.ts file (I am using the src folder) - that's just empty...

src
├── app
│   ├── favicon.ico
│   ├── globals.css
│   ├── layout.tsx
│   └── page.tsx
└── lib
    ├── empty.ts
    └── utils.ts

Docs source: https://nextjs.org/docs/app/api-reference/config/next-config-js/turbopack#resolving-aliases

[Kumneger0]

it worked thanks @icyJoseph

[icyJoseph]

Could you please mark that comment as answer? I am guessing more people will run into this when Turbopack for builds as default hits next@latest

[Kumneger0]

Why is GitHub not showing me a button to mark as answer
it should be around bottom left corner according to thier docs
https://docs.github.com/en/discussions/managing-discussions-for-your-community/moderating-discussions#marking-a-comment-as-an-answer

[icyJoseph]

Oh wow ahah 🤷 GitHub things... I wonder if the discussion type is the problem 🤔 I'll switch it to help.

[DanielSalazarLoaiza]

Turbopack currently doesn’t support resolve.fallback the same way Webpack does — so you can’t directly tell it to replace Node core modules like fs, net, or path with false yet.

The reason is that Turbopack doesn’t polyfill Node.js built-ins for the client bundle at all. It expects client-side code not to import server-only modules.

In other words, while Webpack lets you “silence” imports like fs with:

config.resolve.fallback = { fs: false, net: false }

Turbopack’s model is stricter: if a client bundle references a Node-only module, it will error.

✅ Workarounds:

Use dynamic imports guarded by runtime checks:

if (typeof window === 'undefined') {
  const fs = await import('fs');
}

Move the logic into a Server Component or a server-only utility (server/ folder).

Temporarily disable Turbopack and build with Webpack if you rely on polyfills until feature parity improves.

🧭 Status:
Support for Webpack-style resolve.fallback and module aliasing in Turbopack is still under development — see next.js#53599
for tracking.