title: Android apps doesn't receive FCM notification from my app server
body: <p>My Android apps can receive FCM from Firebase console just fine, however not from my app server.</p>
  
  <p>Here's my snippet of my php script.</p>
  
  <pre><code>$target = 'device code';
  $data = array('message' =&gt; 'Hello','title'=&gt;'FCM Push Notifications');
  
  function sendFCMMessage($data,$target){
     //FCM API end-point
     $url = 'https://fcm.googleapis.com/fcm/send';
     $server_key = 'server key';      
  
     $fields = array();
     $fields['data'] = $data;
     $fields['priority'] = 'high';
     if(is_array($target)){
      $fields['registration_ids'] = $target;
     }else{
      $fields['to'] = $target;
     }
     //header with content_type api key
     $headers = array(
      'Content-Type:application/json',
          'Authorization:key='.$server_key
     );
     //CURL request to route notification to FCM connection server (provided by Google)           
     $ch = curl_init();
     curl_setopt($ch, CURLOPT_URL, $url);
     curl_setopt($ch, CURLOPT_POST, true);
     curl_setopt($ch, CURLOPT_HTTPHEADER, $headers);
     curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
     curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 0);
     curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, false);
     curl_setopt($ch, CURLOPT_POSTFIELDS, json_encode($fields));
     $result = curl_exec($ch);
     if ($result === FALSE) {
      die('Oops! FCM Send Error: ' . curl_error($ch));
     }
     curl_close($ch);
     return $result;
  }
  
  $pn = sendFCMMessage($data,$target);
  echo $pn;
  </code></pre>
  
  <p>but I did received the success response after run my script like this one below.</p>
  
  <pre><code>{
     "multicast_id":4696016312851064849,
     "success":1,
     "failure":0,
     "canonical_ids":0,
     "results":[
        {
           "message_id":"0:1486632797062481%1749d09ff9fd7ecd"
        }
     ]
  }
  </code></pre>