Turbopack Error: failed to write to C:\FOLD\bytelms\.next\dev\server\chunks\ssr\[root-of-the-server]__9cca6895._.js

[isaaccode246]

Turbopack version: b1a04a84
Next.js version: 0.0.0

Error message:

failed to write to C:\FOLD\bytelms\.next\dev\server\chunks\ssr\[root-of-the-server]__9cca6895._.js

Caused by:
- The requested operation cannot be performed on a file with a user-mapped section open. (os error 1224)

[lucasvazq]

This could be a very common problem:

• Turbopack Error: failed to write to C:\Users\charl\Desktop\MyProjects\SPECPlanner\apps\frontend\.next\dev\static\chunks\apps_frontend_src_app_layout_tsx_65325b12._.js #85381
• Turbopack Error: failed to write to \.next\static\chunks\_2916e707._.js.map #80787
• Turbopack Error: failed to write to C:\Users\saidb\Desktop\QuafErp\.next\dev\static\chunks\app_layout_tsx_469ed6a6._.js #85436
• Turbopack Error: failed to write to C:\Users\davic\OneDrive\Documentos\GitHub\dressfy-quiz-1\.next\dev\static\chunks\990bb_next_dist_compiled_react-dom_9fc91627._.js #86692

You are on Windows, so you have two fast approaches here:

Option A: Use WSL

You will need to copy your project inside WSL, then install and run everything again.

Option B: Do not use Turbopack

If you are using a modern version of Next.js, Turbopack is the default tool used internally. However, you can replace it with Webpack.

In package.json, you need to add the --webpack parameter to the dev or build scripts.

Example:

{
  "scripts": {
    "dev": "next dev --webpack"
  }
}

[InfinityZero3000]

This looks like a Windows file-locking issue rather than a Next/Turbopack config problem.
os error 1224 (“user-mapped section open”) typically happens when another process (AV/Defender, indexer, backup/sync tool, or an editor) keeps a handle/memory-map open on a file under .next, so Turbopack can’t rewrite the SSR chunk.
Things to try (in order):

1. Stop the dev server, delete .next, then start again.
2. Temporarily disable or add an exclusion for the project folder (or at least .next) in Windows Defender / antivirus / “Controlled folder access”.
3. If the project is inside a synced/indexed folder (OneDrive/Dropbox, etc.), move it to a normal local folder (e.g. C:\dev\your-app).
4. Close any tools that might scan/build the output (file watchers, backup agents). A full reboot can also clear stale handles.
5. If you’re running on a network drive, try a local disk.
6. As a workaround, run without Turbopack (e.g. next dev --no-turbo) to confirm it’s turbopack+locking related.
   If possible, please share:

• Windows version + filesystem (NTFS?)
• whether Defender/AV is enabled
• whether the repo is under OneDrive/Dropbox
• reproduction steps / minimal repo
  That should help confirm the locking source and whether this is a Turbopack bug or an environment interaction.