Verify canary release

• I verified that the issue exists in the latest Next.js canary release (16.2.0-canary.62 still bundles @vercel/[email protected])

Provide environment information

• Next.js: 16.1.6 (also reproduced on canary)
• Node.js: 24.12.0
• OS: macOS (Darwin 24.5.0)
• Build mode: output: 'standalone'

Which area(s) of Next.js are affected?

Output (Standalone Build), File Tracing

To Reproduce

1. Create a Next.js 16 app with output: 'standalone' and Pages Router
2. Add a dependency that transitively pulls in a package using the module-sync exports condition. For example, axios → [email protected] → [email protected] → [email protected] → [email protected]
3. Create a page with getServerSideProps that uses axios
4. Run next build
5. Start with node .next/standalone/server.js on Node.js >= 22.10
6. Visit the SSR page

Note: Whether this reproduces depends on your lockfile resolving get-intrinsic to 1.3.1 (which added async-function as a dependency). You can force it with npm overrides or yarn resolutions: "get-intrinsic": "1.3.1".

Expected behavior

The standalone server renders the page successfully.

Actual behavior

⨯ Error: Failed to load external module axios-fc13683ac9a02a51: Error: Cannot find module
'/path/to/.next/standalone/node_modules/async-function/require.mjs'
    at Context.externalImport [as y] (.next/server/chunks/ssr/[turbopack]_runtime.js:518:15)

The standalone output contains node_modules/async-function/index.js and package.json, but is missing require.mjs.

Root cause

The async-function package has the following exports in its package.json:

"exports": {
  ".": [
    {
      "module-sync": "./require.mjs",
      "import": "./index.mjs",
      "default": "./index.js"
    },
    "./index.js"
  ]
}

The module-sync condition became a default condition in Node.js 22.10.0 (release notes). At runtime, Node.js >= 22.10 resolves module-sync (higher priority) → require.mjs. But @vercel/nft only traces the default condition → index.js, so require.mjs is never copied to the standalone output.

Fix already available

This was already reported and fixed in @vercel/nft:

• Issue: https://github.com/vercel/nft/issues/531
• PR: https://github.com/vercel/nft/pull/534
• Released: @vercel/[email protected] (July 2025)

Next.js 16.1.6 and canary 16.2.0-canary.62 both still bundle @vercel/[email protected]. Bumping to >= 0.30.0 would fix this.

Workaround

// next.config.mjs
outputFileTracingIncludes: {
  '/**': [
    './node_modules/async-function/require.mjs',
    './node_modules/async-generator-function/require.mjs',
    './node_modules/generator-function/require.mjs',
  ],
},

This is fragile — any new dependency using module-sync exports will require manually adding more entries.

Impact

Node.js 24 is the current LTS. Any Next.js project using standalone output on Node.js >= 22.10 is affected if its dependency tree includes packages with module-sync exports.