Description

Deploying a Hono application with zero configuration to Vercel works successfully. However, when running the API, a runtime error is thrown when using TypeScript path aliases.

Error

Error [ERR_MODULE_NOT_FOUND]: Cannot find package '@/constants' imported from /var/task/src/index.js

Reproduction

Repository: https://github.com/ruchernchong/hono-vercel-path-alias-error

Configuration

tsconfig.json:

{
  "compilerOptions": {
    "target": "ESNext",
    "module": "NodeNext",
    "strict": true,
    "skipLibCheck": true,
    "types": ["node"],
    "jsx": "react-jsx",
    "jsxImportSource": "hono/jsx",
    "outDir": "./dist",
    "baseUrl": ".",
    "paths": {
      "@/*": ["src/*"]
    }
  },
  "exclude": ["node_modules"]
}

package.json:

{
  "name": "hono",
  "type": "module",
  "dependencies": {
    "hono": "^4.9.10"
  }
}

Code Structure

• src/index.ts - imports from @/constants
• src/constants/index.ts - exports the constant

Package Managers Tested

This issue occurs with both:

• Bun
• pnpm

Expected Behavior

Path alias should work during runtime as well.

Environment

• Node.js: v22.18.0
• Hono: v4.9.10
• Module system: ESM ("type": "module")