PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/nestjs/nest/blob/master/CONTRIBUTING.md
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Other... Please describe:

What is the current behavior?

Issue Number: #16179

Error Message

On Windows OS, FileTypeValidator fails when dynamically loading the file-type ESM package with the following error:

Error [ERR_UNSUPPORTED_ESM_URL_SCHEME]: Only URLs with a scheme in: file, data, and node are supported by the default ESM loader. On Windows, absolute paths must be valid file:// URLs. Received protocol 'c:'

Causes

• Window OS Absolute Paths: (e.g., D:\Users\Project\node_modules\file-type\index.js)
• This absolute paths are passed directly to the ESM dynamic import. The ESM loader(in project, load-esm package) interprets the drive letter(e.g., D:) as an invalid URL Scheme instead of recognizing it as a file path.
• This regression was introduced in PR fix(common): resolve file-type path explicitly #16077 when file-type package migrated to ESM-only.

What is the new behavior?

Windows absolute paths are now converted to proper file:// URLs using Node.js's built-in pathToFileURL() function before being passed to loadEsm().

// Before
let fileTypePath: string;
try {
  fileTypePath = require.resolve('file-type');
} catch {
  fileTypePath = 'file-type';
}

// After
import { pathToFileURL } from 'url';

let fileTypeModule: string;
try {
  const resolvedPath = require.resolve('file-type');
  fileTypeModule = pathToFileURL(resolvedPath).href;  // Convert to file:// URL
} catch {
  fileTypeModule = 'file-type';
}

This ensures cross-platform ESM compatibility:

• Windows: D:\path\to\file-type → file:///D:/path/to/file-type
• Unix/macOS: /path/to/file-type → file:///path/to/file-type

Does this PR introduce a breaking change?

• Yes
• No

Other information

Testing

• All existing FileTypeValidator tests pass on Ubuntu, macOS, and Windows
• Verified on Windows environment using GitHub Actions (I'm on macOS, so tested via CI)
• No additional dependencies required - uses Node.js built-in url.pathToFileURL()

Technical Details

• ESM loader officially supports file:// URLs on all platforms
• pathToFileURL() is available in all supported Node.js versions
• This approach follows Node.js ESM documentation recommendations for handling platform-specific absolute paths

Note

• This is my first open source contribution to NestJS, and I'm still learning the contribution process.
• Please let me know if any changes are needed!