While Testing Firebase httpsCallable functions Firebase Client giving "FirebaseError: internal" Error

Steps to Reproduce :

1. Run firebase init to initialize the Firebase Configurable. Then select Functions and Emulators.
2. For Emulators select Functions emulator and ui emulator. Then for Functions emulator assign port as 5001 and for ui assign port as 2000.
3. For Functions select typescript and let firebase download the dependencies. Then paste the following code in functions/index.ts :

import * as functions from "firebase-functions";

export const helloWorld = functions.https.onCall((data, context) => {
    console.log(data);
    return { success : true };
});

4. Run npm run build inside the functions/ folder to build the function. Then start the firebase emulator using firebase emulators: start
5. Now initialize a new project by installing firebase sdk and initializing the SDK with firebaseConfig as follows index.ts:

import { initializeApp } from "firebase/app";
import { connectFunctionsEmulator, getFunctions, httpsCallable } from "firebase/functions";

const firebaseConfig = { /*...firebaseConfig*/ };

const app = initializeApp(firebaseConfig);
const functions = getFunctions(app);
const useEmulator:boolean = true

if(useEmulator) {
    connectFunctionsEmulator(functions, "localhost", 5001);
}

const triggerCallable = httpsCallable(functions, "helloWorld");
const result = await triggerCallable({
    message : "Hello world",
    count: 1
});
console.log(result); // expected : { success : true }

6. Run the index.ts file with npm run build && node dist/index.js, you will get :

node:internal/process/esm_loader:97
    internalBinding('errors').triggerUncaughtException(
                              ^

[FirebaseError: internal] {
  code: 'functions/internal',
  customData: undefined,
  details: undefined
}

> I am not even getting the function intialized message in the emulator logs. Although I do get ✔ functions: Loaded functions definitions from source: helloWorld.

It looks like the function is not even initializing it correctly. I have also tried with onCall() 2nd gen firebase functions and it too has the same result FirebaseError: internal

Resources :

firebase.json :

{
  "functions": [
    {
      "source": "functions",
      "codebase": "default",
      "ignore": [
        "node_modules",
        ".git",
        "firebase-debug.log",
        "firebase-debug.*.log"
      ],
      "predeploy": [
        "npm --prefix \"$RESOURCE_DIR\" run build"
      ]
    }
  ],
  "emulators": {
    "functions": {
      "port": 5001
    },
    "ui": {
      "enabled": true,
      "port": 2000
    },
    "singleProjectMode": true
  }
}

Project Structure :

.
├── database-debug.log
├── dist
│   ├── index.js
│   └── index.js.map
├── firebase-debug.log
├── firebase.json
├── functions
│   ├── lib
│   │   ├── index.js
│   │   └── index.js.map
│   ├── package.json
│   ├── package-lock.json
│   ├── src
│   │   └── index.ts
│   └── tsconfig.json
├── package.json
├── package-lock.json
├── pubsub-debug.log
├── src
│   └── index.ts
├── tsconfig.json
└── ui-debug.log

Where my tsconfig.json of the client app is :

{
    "compilerOptions": {
        "module": "NodeNext",
        "moduleResolution": "NodeNext",
        "target": "ES2020",
        "sourceMap": true,
        "outDir": "dist"
    },
    "include": ["src/**/*"],
}

I have tried everything please somebody help
Thanks in advance.

I think the problem might be related to https://github.com/nodejs/node/issues/40537. TLDR; starting from Node 17 there was a change to the default IP resolving. By default, it now uses the IPv6 loopback address, which is ::1.

Since it looks like the emulator is using the host 127.0.0.1, to resolve this try changing localhost to 127.0.0.1.

if (useEmulator) {
  connectFunctionsEmulator(functions, "127.0.0.1", 5001);
}