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nextjs - 💡(How to fix) Fix [Turbopack] "TypeError: fetch failed" with cause "not implemented... yet..." during SSG build [1 comments, 2 participants]

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vercel/next.js#86867•Fetched 2026-04-08 02:08:47
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ryota-murakamiryota-murakami
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Error Message

TypeError: fetch failed at ignore-listed frames { [cause]: Error: not implemented... yet... at module evaluation (.next/server/chunks/c764c392..js:2:1127) at instantiateModule (.next/server/chunks/[turbopack]_runtime.js:715:9) }

Code Example

TypeError: fetch failed
at ignore-listed frames {
[cause]: Error: not implemented... yet...
at module evaluation (.next/server/chunks/_c764c392._.js:2:1127)
at instantiateModule (.next/server/chunks/[turbopack]_runtime.js:715:9)
}

---

Platform: Ubuntu Linux 24.04
Node: v20.19.6
Next.js: 16.0.7 (Turbopack)
Build Machine: 2 cores, 8 GB

---

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 25.1.0
Binaries:
  Node: 22.18.0
  pnpm: 10.24.0
Relevant Packages:
  next: 16.0.7
  react: 19.2.1
  react-dom: 19.2.1
  typescript: 5.9.3

---

2025-12-05T11:17:05.063Z  ▲ Next.js 16.0.7 (Turbopack)
2025-12-05T11:17:39.936Z  ✓ Compiled successfully in 33.5s
2025-12-05T11:17:53.788Z  Collecting page data using 1 worker ...
2025-12-05T11:17:54.118Z  TypeError: fetch failed
2025-12-05T11:17:54.118Z  at ignore-listed frames {
2025-12-05T11:17:54.118Z  [cause]: Error: not implemented... yet...
2025-12-05T11:17:54.118Z  at module evaluation (.next/server/chunks/_c764c392._.js:2:1127)
2025-12-05T11:17:54.119Z  at instantiateModule (.next/server/chunks/[turbopack]_runtime.js:715:9)
2025-12-05T11:17:54.119Z  }
2025-12-05T11:17:54.496Z  Generating static pages using 1 worker (0/37) ...
2025-12-05T11:17:54.835Z  TypeError: fetch failed
2025-12-05T11:17:54.835Z  at ignore-listed frames {
2025-12-05T11:17:54.836Z  [cause]: Error: not implemented... yet...
2025-12-05T11:17:54.836Z  at d (.next/server/chunks/ssr/027a9_next_dist_1bdaf56b._.js:5:27460)
2025-12-05T11:17:54.837Z  at <unknown> (.next/server/chunks/ssr/027a9_next_dist_1bdaf56b._.js:5:28442)
2025-12-05T11:17:54.837Z  }
2025-12-05T11:18:04.651Z  ✓ Generating static pages using 1 worker (37/37) in 10.2s
RAW_BUFFERClick to expand / collapse

Link to the code that reproduces this issue

https://github.com/laststance/laststance.io

To Reproduce

  1. Clone the repository: git clone https://github.com/laststance/laststance.io
  2. Install dependencies: pnpm install
  3. Build the project: pnpm build
  4. Observe the error in the build output during "Collecting page data" and "Generating static pages" phases

The error also occurs on Vercel deployments with Turbopack enabled.

Current vs. Expected behavior

Current behavior: During next build with Turbopack, the following error is logged:

TypeError: fetch failed
at ignore-listed frames {
[cause]: Error: not implemented... yet...
at module evaluation (.next/server/chunks/_c764c392._.js:2:1127)
at instantiateModule (.next/server/chunks/[turbopack]_runtime.js:715:9)
}

This error occurs during:

  1. "Collecting page data" phase
  2. "Generating static pages" phase

The build completes successfully (all pages generated), but the error is thrown as an unhandled promise rejection. This causes error monitoring tools (like Sentry) to capture it as an issue.

Expected behavior: No unhandled "not implemented... yet..." errors should be thrown during a successful build. If a feature is not yet implemented, it should either:

  1. Be silently handled without throwing
  2. Show a proper warning message
  3. Not reach user-facing error monitoring

Provide environment information

Vercel Build Environment (where error occurs):

Platform: Ubuntu Linux 24.04
Node: v20.19.6
Next.js: 16.0.7 (Turbopack)
Build Machine: 2 cores, 8 GB

Local Environment:

Operating System:
  Platform: darwin
  Arch: arm64
  Version: Darwin Kernel Version 25.1.0
Binaries:
  Node: 22.18.0
  pnpm: 10.24.0
Relevant Packages:
  next: 16.0.7
  react: 19.2.1
  react-dom: 19.2.1
  typescript: 5.9.3

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

Turbopack

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

next build (build)

Additional context

Full build log excerpt from Vercel:

2025-12-05T11:17:05.063Z  ▲ Next.js 16.0.7 (Turbopack)
2025-12-05T11:17:39.936Z  ✓ Compiled successfully in 33.5s
2025-12-05T11:17:53.788Z  Collecting page data using 1 worker ...
2025-12-05T11:17:54.118Z  TypeError: fetch failed
2025-12-05T11:17:54.118Z  at ignore-listed frames {
2025-12-05T11:17:54.118Z  [cause]: Error: not implemented... yet...
2025-12-05T11:17:54.118Z  at module evaluation (.next/server/chunks/_c764c392._.js:2:1127)
2025-12-05T11:17:54.119Z  at instantiateModule (.next/server/chunks/[turbopack]_runtime.js:715:9)
2025-12-05T11:17:54.119Z  }
2025-12-05T11:17:54.496Z  Generating static pages using 1 worker (0/37) ...
2025-12-05T11:17:54.835Z  TypeError: fetch failed
2025-12-05T11:17:54.835Z  at ignore-listed frames {
2025-12-05T11:17:54.836Z  [cause]: Error: not implemented... yet...
2025-12-05T11:17:54.836Z  at d (.next/server/chunks/ssr/027a9_next_dist_1bdaf56b._.js:5:27460)
2025-12-05T11:17:54.837Z  at <unknown> (.next/server/chunks/ssr/027a9_next_dist_1bdaf56b._.js:5:28442)
2025-12-05T11:17:54.837Z  }
2025-12-05T11:18:04.651Z  ✓ Generating static pages using 1 worker (37/37) in 10.2s

The project uses:

  • code-inspector-plugin with Turbopack configuration in next.config.mjs
  • @sentry/nextjs for error monitoring
  • MDX for blog posts with @next/mdx
  • GitHub API calls during SSG via octokit

The error appears to be internal to Turbopack's module loading mechanism, not from user code.

extent analysis

TL;DR

The most likely fix or workaround is to update or configure Turbopack to handle the "not implemented... yet..." error silently or provide a proper warning message.

Guidance

  • Investigate Turbopack configuration options in next.config.mjs to see if there's a way to handle or suppress the "not implemented... yet..." error.
  • Check the code-inspector-plugin configuration to ensure it's not causing the issue with Turbopack.
  • Verify that the GitHub API calls via octokit are not related to the error, as the error appears to be internal to Turbopack.
  • Consider updating Next.js and Turbopack to the latest versions to see if the issue is resolved.

Example

No specific code example is provided, as the issue appears to be related to the internal workings of Turbopack.

Notes

The error seems to be specific to Turbopack's module loading mechanism, and without more information about the Turbopack configuration and the code-inspector-plugin, it's difficult to provide a more specific solution.

Recommendation

Apply a workaround by configuring Turbopack to handle the error silently or provide a proper warning message, as updating to a fixed version is not clearly implied in the issue.

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