Helvetica.afm file missing in Next.js

[james-beston]

Bug Report

No Helvetica.afm file is being created when I use Next.js locally.

Description of the problem

I have to manually create a) the data folder and b) the Helvetica.afm file in .next/server/vendor-chunks every time I start the project.

Code sample

import { NextResponse } from 'next/server';
import PDFDocument from 'pdfkit';

export async function GET() {
  // Create a new PDF document
  const doc = new PDFDocument();

  // Create a buffer to store the PDF data
  const pdfBuffer: Buffer = await new Promise((resolve, reject) => {
    const buffers: Uint8Array[] = [];
    doc.on('data', buffers.push.bind(buffers));
    doc.on('end', () => {
      const pdfData = Buffer.concat(buffers);
      resolve(pdfData);
    });

    // Add content to the PDF document
    doc.fontSize(25).text('Hello, world!', 100, 100);
    doc.fontSize(12).text('This PDF was generated server-side with pdfkit in Next.js.', 100, 150);

    // Finalize the PDF
    doc.end();
  });

  // Return the PDF as a response
  return new NextResponse(pdfBuffer, {
    headers: {
      'Content-Type': 'application/pdf',
      'Content-Length': pdfBuffer.length.toString(),
      'Content-Disposition': 'inline; filename="output.pdf"', // or 'attachment;' for download
    },
  });
}

Your environment

• pdfkit version: 0.15.0
• Node version: 20.12.2
• Next version: 14.2.9
• React version: 18.3.1

[marcoripa96]

did you find a solution? I also have the same error

[Ftwrr]

same here

[marcoripa96]

The correct solution for the current version of next is declaring pdfkit as a serverComponentExternalPackage in the nextjsconfig:

const nextConfig = {
  experimental: {
    serverComponentsExternalPackages: ["pdfkit"],
  },
};

[akulich]

The correct solution for the current version of next is declaring pdfkit as a serverComponentExternalPackage in the nextjsconfig:

const nextConfig = {
  experimental: {
    serverComponentsExternalPackages: ["pdfkit"],
  },
};

This "fix" worked for me on Next.js 14.2.16.

Thank you!

[akulich]

The correct solution for the current version of next is declaring pdfkit as a serverComponentExternalPackage in the nextjsconfig:

const nextConfig = {
  experimental: {
    serverComponentsExternalPackages: ["pdfkit"],
  },
};

This "fix" worked for me on Next.js 14.2.16.

Thank you!

Note that in Next.js 15 serverComponentsExternalPackages seemed to become a production feature as tstikvoort also mentioned in #1467. Here the docs.

So you use:

const nextConfig = {
  serverExternalPackages: ["pdfkit"],
}

[Gerald-ux-ux]

@marcoripa96 Thanks dude it worked🚀

[freemvmt]

@akulich you absolute gem! I have been wrestling with this thing for like 3 days, and this immediately resolved it in all environments in one line 🤦🏼

By that I mean local development with Webpack or Turbopack, local build, and production on Vercel (which was the sticky thing that I couldn't fix before).

In case anyone's interested, I first fixed it on local with some code inspired by this Reddit comment, then with a more elegant solution involving custom Webpack config leveraging the copy-webpack-plugin, but neither of these solutions translated to the production/Vercel build.

[jessicamarin]

For anyone landing here from Google: the root cause is that Next.js bundles your server code, and pdfkit reads its font metrics (.afm files) from disk at runtime — the bundler doesn't know those data files are needed, so they never make it into .next/server. Recreating the folder by hand works until the next build wipes it.

The actual fix is one line of config — tell Next not to bundle pdfkit at all, so it's required from node_modules at runtime with its data files intact:

// next.config.mjs — Next 14
const nextConfig = {
  experimental: {
    serverComponentsExternalPackages: ["pdfkit"],
  },
};

On Next 15 the same option moved out of experimental and is called serverExternalPackages.

Also make sure the route handler runs on Node (export const runtime = "nodejs") — the Edge runtime has no filesystem, so pdfkit can't work there at all.

I wrote up the full route-handler setup (this error plus the other three things that break: Edge runtime, the BodyInit typing on Next 14, and why to buffer instead of stream) here: https://cleanhour.studio/blog/nextjs-pdf-on-the-fly