Summary: Discussions in this issue have diverged a bit, and there are mainly two cases:

1. Turbopack + non-Vercel deployment. Broken since v16.0.3 due to Turbopack starts to trace worker_threads (fixed #84766).
   • Errors (include but not limited to):
     • Parsing ecmascript source code failed (License file) - comment1
     • Can't resolve 'why-is-node-running'/'tap'/etc. (require statement) - comment2, comment3
   • Workaround:
     • Switch back to Webpack. next build --webpack
     • Or add pino, thread-stream and related pino transport target packages to serverExternalPackages, you might also need to add thread-stream as a dependency explicitly.
       • comment4 - Set serverExternalPackages
       • comment5, comment6 - Install thread-stream
       • comment7 - Use shim
       • comment8 - pin to specific versions due to conflicts
   • Fixed: since v16.1.0-canary.16 by #86375 and #86884
2. Turbopack + Vercel deployement. This is the original case of this issue. Turbopack never works in this setup, #84766 was fixed in v16.0.3, and now #86099 is waiting for a fix. The fixes above doesn't work for this case (see https://github.com/vercel/next.js/issues/86099#issuecomment-3629882719). The only workaround is to use Webpack next build --webpack with serverExternalPackages, see Notes below.

Notes: From comment9

Pino is way too dynamic for Turbopack to be able to figure out all required files automatically: pinojs/pino@7dd79a3/lib/transport.js#L94

Pino itself has a documentation that talks about bundling, and there were already problems since Webpack + Vercel deployment, see comment10.

Also for in−depth details: https://github.com/pinojs/thread-stream/issues/184

Link to the code that reproduces this issue

https://github.com/CHC383/nextjs-turbopack-pino-reproduction

To Reproduce

1. Deploy the code to Vercel
2. Visit <url>/api/log
3. Check the log of the Vercel deployment

Current vs. Expected behavior

Current behavior

With Turbopack in NextJs v16, Pino worker thread throws the following error:

Uncaught Exception: Error: Cannot find module './transport-stream'
Require stack:
- /var/task/node_modules/.pnpm/[email protected]/node_modules/pino/lib/worker.js
    at Module._resolveFilename (node:internal/modules/cjs/loader:1420:15)
    at defaultResolveImpl (node:internal/modules/cjs/loader:1058:19)
    at resolveForCJSWithHooks (node:internal/modules/cjs/loader:1063:22)
    at Module._load (node:internal/modules/cjs/loader:1226:37)
    at TracingChannel.traceSync (node:diagnostics_channel:328:14)
    at wrapModuleLoad (node:internal/modules/cjs/loader:244:24)
    at Module.require (node:internal/modules/cjs/loader:1503:12)
    at a (/opt/rust/bytecode.js:2:1094)
    at Object.<anonymous> (/var/task/node_modules/.pnpm/[email protected]/node_modules/pino/lib/worker.js:7:36)
    at Module.<anonymous> (/opt/rust/bytecode.js:2:1435)

Expected behavior

Pino worker thread works without any exception, which is the behavior of using WebPack.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #89-Ubuntu SMP PREEMPT_DYNAMIC Sat Oct 11 01:02:46 UTC 2025
  Available memory (MB): 15839
  Available CPU cores: 20
Binaries:
  Node: 24.11.1
  npm: 11.6.2
  Yarn: N/A
  pnpm: 10.24.0
Relevant Packages:
  next: 16.1.0-canary.16 // Latest available version is detected (16.1.0-canary.16).
  eslint-config-next: N/A
  react: 19.2.1
  react-dom: 19.2.1
  typescript: 5.9.3
Next.js Config:
  output: N/A

Which area(s) are affected? (Select all that apply)

Turbopack

Which stage(s) are affected? (Select all that apply)

Vercel (Deployed)

Additional context

@mischnic This is a follow up of #84766. It seems that with multiple targets, the pino/lib/worker.js is used and not traced by Turbopack properly. I have updated the reproduction code to trigger the new error.