ERR_REQUIRE_ESM

The ERR_REQUIRE_ESM error means you used require() on an ES module. Fix it by using import, renaming to .cjs, or adding "type": "commonjs" to package.json.

What It Means

Since Node.js 12, the module system supports two formats: CommonJS (.js/.cjs, using require() and module.exports) and ES modules (.js/.mjs, using import/export). A file is treated as ESM if its extension is .mjs or if the nearest package.json contains "type": "module". Calling require() on an ESM file throws ERR_REQUIRE_ESM because require() is synchronous and ESM modules are asynchronously loaded.

Why It Happens

• Your package.json has "type": "module" and you’re trying to require() another ESM module.
• You’re using require() on a package that ships only as ESM (e.g., chalk v5+, node-fetch v3+).
• You renamed a file to .mjs but still use require() in a CommonJS file trying to load it.
• You’re mixing module systems in a project that doesn’t have a consistent "type" field.

How to Fix It

1. Use import() instead of require() (dynamic import)

// Instead of:
const chalk = require('chalk');

// Use dynamic import (works in both CJS and ESM):
const chalk = await import('chalk');

Note: import() returns a Promise, so you need async context.

2. Switch your project to ES modules (use import everywhere)

Set "type": "module" in package.json:

{
  "type": "module"
}

Then replace require() with import:

import chalk from 'chalk';
import fs from 'fs/promises';

3. Rename the file to .cjs (keep using require)

If you can’t or don’t want to convert the whole project to ESM, rename the specific file to .cjs:

mv src/config.js src/config.cjs

Then require() works normally on .cjs files regardless of the "type" field.

4. Set "type": "commonjs" explicitly in package.json

{
  "type": "commonjs"
}

This makes .js files default to CommonJS. If the package you’re trying to load is ESM-only (like chalk 5+), you’ll still need to use import() instead of require().

5. Use a bundler (Webpack / Rollup / esbuild)

Bundlers handle module system interop automatically:

npm install --save-dev esbuild
npx esbuild src/index.js --bundle --outfile=dist/bundle.js