after adding server key still showing request was missing an Authentication Key (FCM Token)

[Imran Ahmed]

 am trying to send server notification via firebase to my android apps. I am using xampp local server to test firebase notification from app server. I have followed some tutorial and i have done all the things. my app showing notification from firebase solely, but when i am trying to show notification from app server via firebase its showing `**

The request was missing an Authentication Key (FCM Token). Please, refer to section "Authentication" of the FCM documentation, at https://firebase.google.com/docs/cloud-messaging/server.

` i have tried with adding **server key: AAAAX2m5UCk:********************************************************************n

Also with Legacy server key AI********************D8

my php code to send notification:

<?php

require "init.php";

$message = $_POST['message'];
$title=$_POST['title'];

$path_to_fcm = 'https://fcm.googleapis.com/fcm/send';
$server_key="AAAAX2m5UCk:*********n";

$sql="select fcm_token from fcm_info";

$result = mysqli_query($con,$sql);
$row = mysqli_fetch_row($result);

$key = $row[0];

// var_dump($key);

$fields = array('to' => $key,'data' =>array('title' => $title,'body'=>$message));

$payload = json_encode($fields);

$headers = array(
    "Content-Type: application/json",   
    "Athorization: key=$server_key"
);

// die();

$curl_session = curl_init();
curl_setopt($curl_session, CURLOPT_URL, $path_to_fcm);
curl_setopt($curl_session, CURLOPT_POST, true);
curl_setopt($curl_session, CURLOPT_HTTPHEADER, $headers);
curl_setopt($curl_session, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl_session, CURLOPT_SSL_VERIFYPEER, false);
curl_setopt($curl_session, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
curl_setopt($curl_session, CURLOPT_POSTFIELDS, $payload);

$result = curl_exec($curl_session);

if(curl_error($curl_session))
{
    echo 'error:' . curl_error($curl_session);
}

curl_close($curl_session);

var_dump($result);
// myqsli_close($con);
?>