Node.js: Error [ERR_MODULE_NOT_FOUND]: Cannot find module without file extension in Node ESM
Error [ERR_MODULE_NOT_FOUND]: Cannot find module '/app/src/utils' imported from /app/src/index.js Did you mean to import /app/src/utils.js?
Immediate Remediation
typescript
// 1. In tsconfig.json: Use NodeNext or Bundler module resolution:
{
"compilerOptions": {
"moduleResolution": "bundler",
"module": "ESNext"
}
}
// 2. In Node runtime ESM: Always include explicit .js extension in relative imports:
import { helper } from './utils.js';Root Cause Analysis
Node.js native ECMAScript Modules (ESM) specification does not perform automatic directory index or extension resolution (unlike CommonJS or Webpack).
Verification & Guardrails
- In TypeScript with moduleResolution "NodeNext", import statements must reference .js even though the source is .ts.
- Use moduleResolution "bundler" if targeting Next.js, Vite, or Cloudflare Workers.
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