"Overly broad patterns" warnings during build

[MarcJose]

Hello,

after upgrading our application to next.js 16 we see lots of build warnings from turbopack for a server action which handles file uploads. This only seems to happen when a certain amount of files exists and path.join() or path.resolve() is used.

Is there a way to either fix these warnings, supress them or is it simply a case of not being best practices and files should be somewhere else?

Link to the code that reproduces this issue

https://github.com/MarcJose/nextjs16-turbopack

To Reproduce

The example project reproduces this warning by creating a certain amount of dummy files in the project as postinstall and having a server action to get the path of a file at runtime.

Current vs. Expected behavior

Current:

> turbopack-warning-repro@1.0.0 build
> next build

   ▲ Next.js 16.0.0 (Turbopack)

   Creating an optimized production build ...
Turbopack build encountered 2 warnings:
./src/actions/files.ts:32:24
The file pattern ('/ROOT/public/' <dynamic> '/' <dynamic> | '/ROOT/public' <dynamic> '/' <dynamic> | '/ROOT/public/' <dynamic> | '/ROOT/public' <dynamic>) matches 16000 files in [project]/
  30 |
  31 |   // This also triggers the warning
> 32 |   const resolvedPath = path.resolve(
     |                        ^^^^^^^^^^^^^
> 33 |     baseDir,
     | ^^^^^^^^^^^^
> 34 |     userPath.replace(/^\//, ""),
     | ^^^^^^^^^^^^
> 35 |     fileName
     | ^^^^^^^^^^^^
> 36 |   );
     | ^^^^
  37 |
  38 |   return resolvedPath;
  39 | }

Overly broad patterns can lead to build performance issues and over bundling.

Import trace:
  Server Component:
    ./src/actions/files.ts
    ./src/app/page.tsx


./src/actions/files.ts:20:22
The file pattern ('/ROOT/public/media/' <dynamic> '/' <dynamic> | '/ROOT/public/media' <dynamic> '/' <dynamic> | '/ROOT/public/media/' <dynamic> | '/ROOT/public/media' <dynamic>) matches 32000 files in [project]/
  18 |   // This line triggers the warning:
  19 |   // "The file pattern matches X files... Overly broad patterns can lead to build performance issues"
> 20 |   const targetPath = path.join(mediaDir, folder, filename);
     |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  21 |
  22 |   return targetPath;
  23 | }

Overly broad patterns can lead to build performance issues and over bundling.

Import trace:
  Server Component:
    ./src/actions/files.ts
    ./src/app/page.tsx


 ✓ Compiled successfully in 862.8ms
 ✓ Finished TypeScript in 650.1ms    
 ✓ Collecting page data in 162.0ms    
 ✓ Generating static pages (3/3) in 214.6ms
 ✓ Finalizing page optimization in 3.7ms    

Route (app)
┌ ○ /
└ ○ /_not-found


○  (Static)  prerendered as static content

Expected:

Clean build.

Provide environment information

Operating System:
  Platform: linux
  Arch: x64
  Version: #1 SMP PREEMPT_DYNAMIC Sun, 19 Oct 2025 19:21:18 +0000
  Available memory (MB): 61858
  Available CPU cores: 16
Binaries:
  Node: 22.20.0
  npm: 10.9.3
  Yarn: N/A
  pnpm: N/A
Relevant Packages:
  next: 16.0.0 // Latest available version is detected (16.0.0).
  eslint-config-next: N/A
  react: 19.2.0
  react-dom: 19.2.0
  typescript: 5.9.3
Next.js Config:
  output: N/A

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

Turbopack

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

next build (local)

Additional context

No response

[joshwcomeau]

I’m running into this as well, and weirdly, there aren’t actually that many files in the source directory. It claims to match 27742 files, but there are only 814 files in the relevant directory, and even fewer that match the actual import pattern. I’ll include the full logs below in case it’s helpful, but really I’m just trying to +1 this issue, to find a way to suppress this warning.

Logs and code

Here’s the code:

const ROOT_CONTENT_PATH = path.join(process.cwd(), '/content');

export async function getAllLessonPaths(courseSlug) {
  const courseRootPath = path.join(
    ROOT_CONTENT_PATH,
    `/${courseSlug}`
  );
  const moduleSlugs = getDirectories(courseRootPath);

  let lessonPaths = [];

  for (const moduleSlug of moduleSlugs) {
    const moduleRootPath = path.join(
      ROOT_CONTENT_PATH,
      `/${courseSlug}/${moduleSlug}`
    );

   const lessonFilenames = fs
      .readdirSync(moduleRootPath)
      .filter(
        (filename) =>
          /\.mdx$/.test(filename) && filename !== 'index.mdx'
      )
      .map((filename) => ({
        moduleMetadata,
        moduleSlug,
        lessonSlug: filename.replace(/\.mdx$/, ''),
        lessonPath: path.join(
          ROOT_CONTENT_PATH,
          `/${courseSlug}/${moduleSlug}/${filename}`
        ),
      }));

    lessonPaths.push(...lessonFilenames);
  }

  return lessonPaths;
}

And here’s the logs, claiming that there are way more files than actually exist:

The file pattern ('/ROOT/content//' <dynamic> '/' <dynamic> '/' <dynamic> | '/ROOT/content/' <dynamic> '/' <dynamic> '/' <dynamic>) matches 16330 files in [project]/
  44 |         moduleSlug,
  45 |         lessonSlug: filename.replace(/\.mdx$/, ''),
> 46 |         lessonPath: path.join(
     |                     ^^^^^^^^^^
> 47 |           ROOT_CONTENT_PATH,
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 48 |           `/${courseSlug}/${moduleSlug}/${filename}`
     | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 49 |         ),
     | ^^^^^^^^^^
  50 |       }));
  51 |
  52 |     lessonPaths.push(...lessonFilenames);
Overly broad patterns can lead to build performance issues and over bundling.
./content/content.helpers.js:157:22
The file pattern ('/ROOT/content//' <dynamic> '/' <dynamic> '//' <dynamic> | '/ROOT/content/' <dynamic> '/' <dynamic> '//' <dynamic> | '/ROOT/content//' <dynamic> '/' <dynamic> '/' <dynamic> | '/ROOT/content/' <dynamic> '/' <dynamic> '/' <dynamic>) matches 27742 files in [project]/
  155 |   const lessons = [];
  156 |   for (const filename of lessonFilenames) {
> 157 |     const filePath = path.join(moduleUrl, `/${filename}`);
      |                      ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  158 |     const slug = filename.replace('.mdx', '');
  159 |
  160 |     const data = await getFrontmatterForFile(filePath);
Overly broad patterns can lead to build performance issues and over bundling.