Error CodeLab Firebase Cloud Functions, cannot send notification by FCM.

### [REQUIRED] Codelab info

CodeLab Firebase Cloud Functions [10. New Message Notifications](https://firebase.google.com/codelabs/firebase-cloud-function

### [REQUIRED] Project setup

I clone project from here.

First I follow CodeLab Firebase Hosting FriendlyChat, and I can complete it.

After that, I started to learn CodeLab Firebase Cloud Functions from [6. The Functions Directory](https://firebase.google.com/codelabs/firebase-cloud-functions#5) by copy folder "codelab-friendlychat-web-main\cloud-functions-start\functions" into my existed CodeLab Firebase Hosting FriendlyChat.

I can follow instuction then success to [8. Welcome New Users](https://firebase.google.com/codelabs/firebase-cloud-functions#7)

Then, I skip [9. Images moderation](https://firebase.google.com/codelabs/firebase-cloud-functions#8), because I think I do not need to know.

### [REQUIRED] Describe the problem

Then at [10. New Message Notifications](https://firebase.google.com/codelabs/firebase-cloud-functions#9), I follow instruction and coding. But when I test FriendlyChat web, it did not have notification message to display.

I went to my FriendlyChat project on Firebase Console. Goto Functions and found there error.

`Error: An error occurred when trying to authenticate to the FCM servers. Make sure the credential used to authenticate this SDK has the proper permissions. See https://firebase.google.com/docs/admin/setup for setup instructions. Raw server response: " `

It cannot send notification by FCM.

Belows are more detail




I am not sure, why there is security error problem. Because I follow instruction.

below is my cloud function code.

```
// TODO(DEVELOPER): Import the Cloud Functions for Firebase and the Firebase Admin modules here.
// Import the Firebase SDK for Google Cloud Functions.
const functions = require('firebase-functions');
// Import and initialize the Firebase Admin SDK.
const admin = require('firebase-admin');
admin.initializeApp();

// TODO(DEVELOPER): Write the addWelcomeMessages Function here.
// Adds a message that welcomes new users into the chat.
exports.addWelcomeMessages = functions.auth.user().onCreate(async (user) => {
functions.logger.log('A new user signed in for the first time.');
const fullName = user.displayName || 'Anonymous';

// Saves the new welcome message into the database
// which then displays it in the FriendlyChat clients.
await admin.firestore().collection('messages').add({
name: 'Firebase Bot',
profilePicUrl: '/images/firebase-logo.png', // Firebase logo
text: `${fullName} signed in for the first time! Welcome!`,
timestamp: admin.firestore.FieldValue.serverTimestamp(),
});
functions.logger.log('Welcome message written to database.');
});

// TODO(DEVELOPER): Write the blurOffensiveImages Function here.

// TODO(DEVELOPER): Write the sendNotifications Function here.
// Sends a notifications to all users when a new message is posted.
exports.sendNotifications = functions.firestore.document('messages/{messageId}').onCreate(async (snapshot) => {
// Notification details.
const text = snapshot.data().text;
const payload = {
notification: {
title: `${snapshot.data().name} posted ${text ? 'a message' : 'an image'}`,
body: text ? (text.length <= 100 ? text : text.substring(0, 97) + '...') : '',
icon: snapshot.data().profilePicUrl || '/images/profile_placeholder.png',
click_action: `https://${process.env.GCLOUD_PROJECT}.firebaseapp.com`,
}
};

// Get the list of device tokens.
const allTokens = await admin.firestore().collection('fcmTokens').get();
const tokens = [];
allTokens.forEach((tokenDoc) => {
tokens.push(tokenDoc.id);
});

if (tokens.length > 0) {
// Send notifications to all tokens.
const response = await admin.messaging().sendToDevice(tokens, payload);
await cleanupTokens(response, tokens);
functions.logger.log('Notifications have been sent and tokens cleaned up.');
}
});
```

below are firebase packages version in package.json

`"dependencies": {
"@google-cloud/vision": "^2.4.0",
"firebase-admin": "^9.9.0",
"firebase-functions": "^3.14.1"
}`

Please advise me, how can I fix this proble?

Thank you very much