next dev --turbopack does not support using @next/bundle-analyzer - throws warning

[Austin1serb]

Link to the code that reproduces this issue

https://github.com/Austin1serb/next-turbopack-issue

To Reproduce

1. Clone the reproduction repo

  git clone https://github.com/Austin1serb/next-turbopack-issue
  cd next-turbopack-issue
  pnpm install # or npm install

2. Start the development server using Turbopack

pnpm run dev --turbo

3. Observe the following console warnings:

⚠ Webpack is configured while Turbopack is not, which may cause problems.
⚠ See instructions if you need to configure Turbopack: https://nextjs.org/docs/app/api-reference/next-config-js/turbo

4. Now open next.config.js and replace this line:

export default withAnalyzer(nextConfig)

with:

export default nextConfig

Then rerun the dev server — the warnings disappear.

Current vs. Expected behavior

Current behavior: When using @next/bundle-analyzer with next dev --turbo, Next.js logs Webpack-related warnings even though the intention is to use Turbopack. The message is confusing because the user may not be explicitly using Webpack — it's indirectly triggered by the analyzer config. But does not tell the user so.

Expected behavior: Either:

Turbopack should detect and gracefully skip incompatible tools like @next/bundle-analyzer, or

Documentation should clearly state that @next/bundle-analyzer is not compatible with Turbopack in dev, and the warnings should be more helpful, because doing exactly what they docs say, should not lead to a warning.

At the very minimum it should tell the user that next/bundle-analyzer it the cause of the warning, and what to do from there.

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.3.0: Thu Jan  2 20:23:36 PST 2025; root:xnu-11215.81.4~3/RELEASE_ARM64_T8112
  Available memory (MB): 16384
  Available CPU cores: 8
Binaries:
  Node: 20.16.0
  npm: 10.8.2
  Yarn: 1.22.22
  pnpm: 10.6.5
Relevant Packages:
  next: 15.3.0-canary.20 // Latest available version is detected (15.3.0-canary.20).
  eslint-config-next: N/A
  react: 19.0.0
  react-dom: 19.0.0
  typescript: 5.8.2
Next.js Config:
  output: N/A

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

Turbopack, create-next-app

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

next dev (local)

Additional context

No response