[Turbopack] Styles from SCSS module not loading when not-found.tsx is present (Turbopack only)

[GlebKodrik]

Link to the code that reproduces this issue

https://github.com/GlebKodrik/Next-js-turbopack

To Reproduce

1. Use Next.js with Turbopack (next dev --turbo)
2. Have both PageLayout.module.scss and not-found.tsx in the project
3. Styles from the SCSS module fail to load (class PageLayout-module-scss)

Current vs. Expected behavior

1. No styles applied when not-found.tsx exists
2. Removing not-found.tsx immediately fixes the styling

Provide environment information

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 24.6.0: Mon Jul 14 11:30:40 PDT 2025; root:xnu-11417.140.69~1/RELEASE_ARM64_T8132
  Available memory (MB): 24576
  Available CPU cores: 10
Binaries:
  Node: 20.14.0
  npm: 10.7.0
Relevant Packages:
  next: 15.4.6
  eslint-config-next: N/A
  react: 19.1.0
  react-dom: 19.1.0
  typescript: 5.8.3
Next.js Config:
  output: standalone

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

CSS

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

next dev (local)

Additional context

No response

[GlebKodrik]

This issue first appeared in my actual project (not just a minimal reproduction). The behavior was even stranger there—styles would flicker unpredictably when navigating between pages (sometimes loading, sometimes disappearing).

[GlebKodrik]

If you don't use turbopack, everything works perfectly.

[GlebKodrik]

@icyJoseph Can you please look at the problem? 🥺

[mischnic]

Please try the latest canary (npm add -D next@canary), this should already be fixed.

[GlebKodrik]

@mischnic Yes, everything works with the canary

But there is another error on the production project, which was not there before

[mischnic]

Yeah, I'm currently in the progress of fixing that regression.
v15.4.2-canary.35 works

[GlebKodrik]

and when will the release be with the fix not in the canary? If it's not a secret

[github-actions]

This closed issue has been automatically locked because it had no new activity for 2 weeks. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.