Node.js Error: ERR_REQUIRE_ESM — Cannot Require ESM

Error [ERR_REQUIRE_ESM]: require() of ES Module
/app/node_modules/node-fetch/src/index.js from /app/server.js not supported.
Instead change the require of /app/node_modules/node-fetch/src/index.js in
/app/server.js to a dynamic import() which is available in all CommonJS modules.
    at Object.<anonymous> (/app/server.js:1:14) {
  code: 'ERR_REQUIRE_ESM'
}

ERR_REQUIRE_ESM shows up the moment a package you depend on goes ESM-only and your code is still CommonJS. The Node CJS loader is synchronous; ESM is asynchronous; the two can’t be bridged via require(). Node throws rather than guess.

Three fixes, in priority order: migrate your code to ESM (cleanest), use dynamic import() (least invasive), or pin the package to its last CJS-compatible major (buys time). Almost every Node project hits this at least once during the 2022-2026 ecosystem-wide ESM migration; the boring fixes are well-trodden.

Why this happens

• Package went ESM-only in a major version bump. node-fetch v3, chalk v5, got v12, nanoid v4, p-limit v4, file-type v17, and many others ship pure ESM. Your package.json upgraded across the breaking version (e.g., `^2.6.0` → `^3.0.0`) and your CommonJS code can no longer require them.
• Mixed CJS/ESM project without correct package.json. Your project is CommonJS (no `"type"` field, defaults to CJS) but you installed an ESM-only dep. Or you set `"type": "module"` but your tooling (ts-node, jest, eslint configs) still loads code as CJS.
• TypeScript transpiles import to require. `import fetch from 'node-fetch'` looks like ESM in your `.ts` source, but if `tsconfig.json` has `"module": "commonjs"` (the default for older targets), tsc emits `require('node-fetch')` — which then hits ERR_REQUIRE_ESM at runtime.
• Bundler bundles for CJS but a dependency is ESM-only. Webpack, esbuild, or tsc emits CJS output. The bundle then `require()`s a transitive ESM-only dep at runtime. The bundler can't statically resolve ESM-from-CJS without dual-package handling.
• ts-node, jest, or eslint config running in CJS mode. Default ts-node uses CJS. Jest's transform emits CJS. ESLint's flat config loader is CJS. All of these hit ERR_REQUIRE_ESM the moment you reference an ESM-only package from configs they load.

How to fix it

Fixes are ordered by likelihood. Start with the first one that matches your context.

// Was: const fetch = require('node-fetch');
import fetch from 'node-fetch';

// ESM doesn't have __dirname / __filename — use:
import { fileURLToPath } from 'node:url';
import { dirname } from 'node:path';
const __filename = fileURLToPath(import.meta.url);
const __dirname = dirname(__filename);

const res = await fetch('https://example.com');
console.log(await res.text());

// CommonJS file, but uses ESM-only node-fetch via dynamic import.
async function main() {
  const { default: fetch } = await import('node-fetch');
  const res = await fetch('https://example.com');
  console.log(await res.text());
}

main().catch((err) => {
  console.error(err);
  process.exit(1);
});

{
  "dependencies": {
    "node-fetch": "^2.7.0",
    "chalk": "^4.1.2",
    "got": "^11.8.6",
    "nanoid": "^3.3.7"
  }
}

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "esModuleInterop": true,
    "strict": true
  }
}

const { createRequire } = require('node:module');
const requireCjs = createRequire(import.meta.url);
const cjsTwin = requireCjs('some-pkg/cjs');

Detection and monitoring in production

ERR_REQUIRE_ESM is a startup error — it crashes your process before any traffic flows. CI catches it if you run the full app on every PR. For dependency upgrades, use `npm outdated` and read the changelog of every major bump; ESM-only is almost always called out. Renovate/Dependabot can be configured to pin majors and require manual review for the ones that go ESM.