Turbopack Error: Failed to write app endpoint /page

[IAm-cole]

Turbopack version: c0b086c6
Next.js version: 0.0.0

Error message:

Failed to write app endpoint /page

Caused by:
- [project]/Downloads/Telegram Desktop/IpSentinel/IpSentinel/app/globals.css [app-client] (css)
- reading file C:\Users\HP\Downloads\Telegram Desktop\IpSentinel\IpSentinel\nul
- Incorrect function. (os error 1)

Debug info:
- Execution of get_written_endpoint_with_issues_operation failed
- Execution of endpoint_write_to_disk failed
- Execution of <AppEndpoint as Endpoint>::output failed
- Failed to write app endpoint /page
- Execution of AppEndpoint::output failed
- Execution of AppProject::app_module_graphs failed
- Execution of *<AppEndpoint as Endpoint>::additional_entries failed
- Execution of *ModuleGraph::from_graphs failed
- Execution of SingleModuleGraph::new_with_entries_visited_intern failed
- [project]/Downloads/Telegram Desktop/IpSentinel/IpSentinel/app/globals.css [app-client] (css)
- Execution of primary_chunkable_referenced_modules failed
- Execution of <CssModuleAsset as Module>::references failed
- Execution of parse_css failed
- Execution of <PostCssTransformedAsset as Asset>::content failed
- Execution of PostCssTransformedAsset::process failed
- Execution of <DiskFileSystem as FileSystem>::read failed
- reading file C:\Users\HP\Downloads\Telegram Desktop\IpSentinel\IpSentinel\nul
- Incorrect function. (os error 1)

[hwajongpark]

This looks like a Windows reserved-name issue, not a missing page.tsx issue.

The important line is:

reading file C:\Users\HP\Downloads\Telegram Desktop\IpSentinel\IpSentinel\nul

On Windows, NUL is a reserved device name, so a real file or folder named nul can make normal file reads fail with errors like Incorrect function. Microsoft documents NUL alongside other reserved names here: https://learn.microsoft.com/en-us/windows/win32/fileio/naming-a-file

I would try this:

1. Check whether there is a file/folder named nul in the project root:

Get-ChildItem -Force "C:

[Mehrdoost]

hey @IAm-cole , good catch by @hwajongpark , definitely the nul path. I ran into the same thing on a Windows project last month. The globals.css import tree somehow resolves to a literal nul file — probably a broken PostCSS plugin or a misconfigured custom processor.

To fix it step by step:

Check if there's actually a file/folder named nul in the project root (Windows normally blocks it, but sometimes git or WSL leaves one):

Get-ChildItem -Force "C:\Users\HP\Downloads\Telegram Desktop\IpSentinel\IpSentinel" | Where-Object { $_.Name -eq 'nul' }
If it shows something, delete it with Remove-Item -Force -LiteralPath "C:\Users\HP\Downloads\Telegram Desktop\IpSentinel\IpSentinel\nul"

If there's no file named nul, the problem is inside your CSS. Open globals.css and search for any @import or url() that might resolve to just nul (e.g., url(nul) without quotes, or a misconfigured PostCSS mixin). Remove or fix those.

Temporarily disable PostCSS to isolate: rename postcss.config.js to _postcss.config.js.old, delete .next and node_modules/.cache, then restart dev. If the error disappears, one of your PostCSS plugins is generating bad file references.

As a permanent guard, add a .gitignore rule so no one accidentally commits a nul file:

# Reserved Windows filenames
nul
CON
PRN
AUX

Then git rm --cached nul if it's tracked.

This is 100% a filesystem naming collision, not a missing page. Once the nul reference is gone, the "Next.js version: 0.0.0" part should fix itself (it's just Turbopack's fallback when the whole build fails).

If you're still stuck, drop the contents of your globals.css and PostCSS config here — happy to take a look.