为什么在PHP firebase rest api中出现无效密钥类型错误？ <?php // API access key from Google API's Console define('API_ACCESS_KEY','AIzaSyDvkI

为什么在PHP firebase rest api中出现无效密钥类型错误？

<?php // API access key 
from Google API's Console
define('API_ACCESS_KEY','AIzaSyDvkIrQby4Zz_9YMGYwk###TjqftHM5IPw');

$receiver = 
$_POST['receiver']; 
$body = $_POST['body']; 
$title= $_POST['title']; 
// prep the bundle 
$msg = array ( 'body' => 
$body,
'title' => $title ); 
$fields = array ( 'to' =>'/topics/'.$receiver,'notification' => $msg ); 
 $headers = array(
'Authorization: key='.API_ACCESS_KEY,'Content-Type: application/json');
$ch = curl_init(); 
curl_setopt($ch,CURLOPT_URL,'https://fcm.googleapis.com/fcm/send');curl_setopt($ch,CURLOPT_POST,true );
curl_setopt($ch,CURLOPT_HTTPHEADER, $headers );
curl_setopt( $ch,CURLOPT_RETURNTRANSFER, true );
curl_setopt( $ch,CURLOPT_SSL_VERIFYPEER, false );
curl_setopt( $ch,CURLOPT_POSTFIELDS, json_encode( $fields ) );
$result = curl_exec($ch );
curl_close( $ch );
echo $result;?>