Serverless Functions type: "module" got error

[Lmmmmmm-bb]

Summary

I have a Telegram bot deploy by Vercel Serverless Functions.
Everything was fine when I deployed it before, but recently I found an error when I redeployed it.

1. I used Edge Functions to deploy in this commit.
2. I found the error in the Edge Functions when I deployed it after committing, I reverted the code. relate commit
3. After the second step, the code should be unchanged compared to before. However, after redeploying the Telegram bot, the following error occurs. relate commit
   

Returned to normal after I delete the package.json type: "module" field.

I am curious why the bot did not get this error when it was deployed before.

This is repository https://github.com/Lmmmmmm-bb/m-record-bot. Any help is greatly appreciated!

Additional information

No response

Example

No response

[duiker101]

I think I have a related issue.

My app doesn't use "type":"module" and on current deploy (same code as before) now I get this.

Adding the "type":"module" still breaks with this error

Dev environment seems to work ok. This is preventing me from deploying ATM so any solution would be appreciated.

[tmilar]

I started having the same issue since Friday, for any new deployment I do since that moment.
Looks like any Typescript API function stopped working, as if something broke in the build process in Vercel side.

Even a very basic function like this doesn't work for me:

// ./api/hello.ts
import type { VercelRequest, VercelResponse } from '@vercel/node'

export default function (req: VercelRequest, res: VercelResponse) {
  const { name = 'World' } = req.query
  res.send(`Hello ${name}!`)
}

Results in response:

The logs show:

My tsconfig.json file:

{
  "compilerOptions": {
    "target": "es6",
    "lib": ["dom", "dom.iterable", "esnext"],
    "allowJs": true,
    "skipLibCheck": true,
    "esModuleInterop": true,
    "allowSyntheticDefaultImports": true,
    "sourceMap": true,
    "strict": true,
    "pretty": true,
    "noUnusedLocals": true,
    "noUnusedParameters": true,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "forceConsistentCasingInFileNames": true,
    "module": "esnext",
    "moduleResolution": "node",
    "resolveJsonModule": true,
    "isolatedModules": true,
    "noEmit": true,
    "jsx": "react"
  },
  "include": ["src"],
  "exclude": ["**/node_modules", "**/.*/", "dist", "public", "test", "api"]
}

My package.json:

{
  "name": "my-project",
  "version": "0.1.0",
  "private": true,
  "scripts": {
    "start": "react-scripts start",
    "start:server": "cd api && npm start",
    "start:vercel": "vercel dev",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject",
    "lint": "tsc --noEmit && eslint . --ext \"ts,tsx\"",
    "lint:fix": "npm run lint -- --fix",
    "clean": "rm -rf dist"
  },
  "dependencies": {
    "@auth0/auth0-react": "1.1.0",
    "@vercel/node": "1.10.0",
    "auth0-js": "9.14.0",
    "axios": "^0.27.2",
    "connected-react-router": "6.8.0",
    "date-fns": "^2.28.0",
    "got": "11.8.2",
    "history": "^4.10.1",
    "i18next": "^21.6.3",
    "i18next-browser-languagedetector": "^6.1.2",
    "jsonwebtoken": "8.5.1",
    "jwks-rsa": "2.0.3",
    "lodash": "4.17.20",
    "query-string": "6.13.6",
    "react": "16.13.1",
    "react-csv": "2.0.3",
    "react-dom": "16.13.1",
    "react-i18next": "^11.15.1",
    "react-redux": "7.2.1",
    "react-router-dom": "5.2.0",
    "react-scripts": "3.4.3",
    "recharts": "2.0.9",
    "redux-logger": "3.0.6",
    "redux-saga": "1.1.3",
    "semantic-ui-css": "2.4.1",
    "semantic-ui-react": "1.3.1",
    "typesafe-actions": "5.1.0"
  },
  "devDependencies": {
    "@testing-library/jest-dom": "5.11.4",
    "@testing-library/react": "11.0.4",
    "@testing-library/user-event": "12.1.6",
    "@types/auth0-js": "9.14.0",
    "@types/jest": "26.0.14",
    "@types/jsonwebtoken": "^8.5.6",
    "@types/lodash": "4.14.164",
    "@types/node": "14.11.2",
    "@types/react": "16.9.49",
    "@types/react-csv": "1.1.2",
    "@types/react-dom": "16.9.8",
    "@types/react-redux": "7.1.9",
    "@types/react-router-dom": "5.1.5",
    "@types/redux-logger": "3.0.8",
    "@types/segment-analytics": "^0.0.34",
    "@typescript-eslint/eslint-plugin": "4.3.0",
    "@typescript-eslint/parser": "4.3.0",
    "eslint": "6.8.0",
    "eslint-config-prettier": "6.12.0",
    "eslint-plugin-import": "2.22.1",
    "eslint-plugin-jsx-a11y": "6.3.1",
    "eslint-plugin-prettier": "3.1.4",
    "eslint-plugin-react": "7.21.2",
    "prettier": "2.1.2",
    "typescript": "4.0.3"
  },
}

[steelballs]

I had the same issue on Friday too. It seems to have started occurring after an update to vercel CLI which is used during the deployment.

This deployment worked as expected.

This deployment broke.

[krystof-k]

Yes, the same for me, also happening since Friday. Same commit built now results in the following error:

[POST] /api/answers
17:45:21:77
2023-01-08T16:45:22.267Z	undefined	ERROR	ReferenceError: exports is not defined in ES module scope
This file is being treated as an ES module because it has a '.js' file extension and '/var/task/frontend/package.json' contains "type": "module". To treat it as a CommonJS script, rename it to use the '.cjs' file extension.
    at file:///var/task/frontend/api/answers/index.js:2:23
    at ModuleJob.run (node:internal/modules/esm/module_job:193:25)
    at async Promise.all (index 0)
    at ESMLoader.import (node:internal/modules/esm/loader:530:24)
    at importModuleDynamicallyWrapper (node:internal/vm/module:438:15)
    at getListener (/var/task/___vc/__launcher.js:37:11)
RequestId: 1251019d-68fe-469d-9b70-5c799a343823 Error: Runtime exited with error: exit status 1
Runtime.ExitError

Probably introduced by vercel/vercel#7954. Is there a way to downgrade the CLI?

[danielkraus]

The same. Reproduced the same error on my localhost after upgrading the Vercel CLI to 28.10.3. It must be it.

[steelballs]

Yeah I did a tonne of investigation and testing and it does seem like 28.10.3 is the cause of the issue.

[styfle]

If you have tsconfig.json with module: esnext, then your package.json should have type: module.

If you don’t want to use ESM, you can change tsconfig.json to module: commonjs.

[duiker101]

Just tried to set "module": "commonjs" in tsconfig, I do not have type: module in my package.json.

Still same error:

2023-01-08T18:59:50.401Z	undefined	ERROR	(node:8) Warning: To load an ES module, set "type": "module" in the package.json or use the .mjs extension.
(Use `node --trace-warnings ...` to show where the warning was created)
2023-01-08T18:59:50.403Z	undefined	ERROR	/var/task/api/______.js:1
import { ______ } from "./______";
^^^^^^
SyntaxError: Cannot use import statement outside a module

[danielkraus]

The error occurs while "module: esnext" and "type: module".

[steelballs]

We tried a lot of the suggestions we found on Google, but not a single combinations worked. Would be good to hear from the Vercel team regards what changed between the CLI versions and how the deployment issues can be fixed.

[krystof-k]

I just got a response from Vercel support. It is possible to downgrade the CLI.

Set VERCEL_CLI_VERSION environment variable to the previous CLI verison vercel@28.10.2.

Builds are passing fine again.

[krystof-k]

I've been told "while our engineers work on an update" so I assume it may be a bug but we have to wait. I still think it can be because of a wrong TS configuration.

[danielkraus]

Thank you!!

[swarnava]

Please do not forget to remove the Environment variable once we fix the issue. Thank you for your patience! :)

[Palmaswell]

Thanks so much for providing a solution. I encountered a similar problem fixed by downgrading the Vercel CLI package.

[natapg]

thanks! I've been all morning trying to fix this problem

[swarnava]

We are locking this thread now to avoid confusion. As a next step:

We have an update from our engineer that may fix your issue and allow you to remove the CLI variable:
 
A tsconfig.json with "module": "esnext" (or "module": "nodenext") must also have package.json with "type": "module".

If you run into a problem, it will likely be at runtime and look something like:

ReferenceError: require is not defined in ES module scope, you can use import instead

If you want to continue using CommonJS instead of ES Modules, the solution would be to update your tsconfig.json file with "module": "commonjs".

Also note that TypeScript will allow you to mix CJS and ESM, however Node.js will not. So you cannot use require() and import() in the same file, and you cannot use export default and module.exports in the same file.
 
If you are still facing issue with above configuration, please reach out to Vercel Support with following information:

• contents of package.json
• contents tsconfig.json
• the runtime error message (we can find this if you provide deployment url)
• the contents of the file that failed (the file will be mentioned in the error message)

If you have set any Environment variable to use previous version of Vercel CLI, please ensure you remove it to get future updates of our Vercel builder. Thank you!

[smaeda-ks]

Also, when switching to ESM with the above suggestion and you still see errors such as:

Error: Cannot find module 'xxxx' imported from yyyy

Please make sure you're following the right rules...
https://www.typescriptlang.org/docs/handbook/esm-node.html

We've been seeing users are not aware of the file extension thing, particularly:

• relative import paths need full extensions (e.g we have to write import "./foo.js" instead of import "./foo")