Windows/Next.js: ESM loader error with worker path protocol

[Mavni]

Environment

• Node.js version: 24.x
• pdf-parse version: 2.4.5
• OS: Windows 11
• Framework: Next.js 16.0.10 (Turbopack)

Description

When using pdf-parse v2.4.5 in a Next.js API route on Windows, the worker setup fails with an ESM loader protocol error.

Error Message

Setting up fake worker failed: "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 'e:'"

Steps to Reproduce

1. Create a Next.js project with an API route that uses pdf-parse v2
2. Use the documented approach from troubleshooting:

const { CanvasFactory, getPath } = require('pdf-parse/worker');
const { PDFParse } = require('pdf-parse');

PDFParse.setWorker(getPath());  // Fails on Windows
// Also tried:
PDFParse.setWorker(getData());  // Same error

1. Call the API route to parse a PDF

Expected Behavior

The worker should initialize correctly using either getPath() or getData().

Actual Behavior

The worker fails to set up because the path returned by getPath() uses a Windows drive letter (e.g., e:\path\to\worker.js) instead of a proper file:// URL that the ESM loader expects.

Possible Fix

The getPath() function should convert Windows paths to proper file:// URLs using Node.js url.pathToFileURL():

import { pathToFileURL } from 'node:url';

function getPath() {
  const workerPath = /* current implementation */;
  return pathToFileURL(workerPath).href;
}

Workaround

Switched to unpdf which includes a serverless-optimized pdfjs-dist build with inlined worker that works correctly on Windows and Next.js.

Additional Context

• Added serverExternalPackages: ['pdf-parse', '@napi-rs/canvas'] to next.config.js as documented
• Tried both ESM and CJS import patterns
• Node.js ESM loader on Windows requires file:// protocol for absolute paths

[SyedAhsanFatmi]

I have also tried all the fixes you've mentioned so far and was just about to see if serverExternalPackages fix would work ( build is in process ). But it seems like it will fail.
Thanks for refering @unpdf

[mehmet-kozan]

Have you checked out this repo? https://github.com/mehmet-kozan/vercel-next-app-demo?