title: Firebase Messaging unregister notification for read_timeout failed
body: <p>I was trying to send a notification from one device to another device to let the user know there is a waiting message for him.</p>
  <p>When I was trying to catch and handle the RemoteMessage this is what console prints. It happens on iOS physical devices.</p>
  <p>That function works perfectly before but now it is impossible to send notification to other user over the device, client side.</p>
  <p>Function overview:</p>
  <pre><code>  static Future&lt;void&gt; sendNotificationToOtherUser(
        String title, String body, String token) async {
      final headers = {
        'content-type': 'application/json',
        'Authorization':
            'key={I hide KEY but I assure you there is nothing wrong with key}'
      };
      List&lt;String&gt; list = List();
  // token is not null
      list.add(token);
      final postUrl = 'https://fcm.googleapis.com/fcm/send';
      final data = {
        &quot;registration_ids&quot;: list,
        &quot;notification&quot;: {
          &quot;title&quot;: '$title',
          &quot;body&quot;: '$body',
        },
      };
  
      final response = await http.post(Uri.parse(postUrl),
          body: json.encode(data),
          encoding: Encoding.getByName('utf-8'),
          headers: headers);
  
      if (response.statusCode == 200) {
        // it prints 200 so works perfectly
        print(response.body);
        print('test ok push CFM');
        return true;
      } else {
        print(response.body);
        print(' CFM error');
        // on failure do sth
        return false;
      }
    }
  
  </code></pre>
  <p>It seems everything works but other device cannot catch Notification and shows it due to error I put below.
  Error:</p>
  <pre><code>
  [connection] nw_endpoint_handler_set_adaptive_read_handler [C6.1 216.58.212.42:443 ready channel-flow (satisfied (Path is satisfied), viable, interface: en0, ipv4, dns)] unregister notification for read_timeout failed
  [connection] nw_endpoint_handler_set_adaptive_write_handler [C6.1 216.58.212.42:443 ready channel-flow (satisfied (Path is satisfied), viable, interface: en0, ipv4, dns)] unregister notification for write_timeout failed
  
  </code></pre>
  <p>Libraries:</p>
  <pre><code>  firebase_core: ^1.0.3
    firebase_auth: ^1.0.2
    cloud_firestore: ^1.0.4
    firebase_storage: ^8.0.1
    firebase_messaging: ^10.0.0
  </code></pre>
  <p>Flutter SDK version:</p>
  <pre><code>[✓] Flutter (Channel stable, 2.2.2, on macOS 11.4 20F71 darwin-x64, locale
      en-GB)
      • Flutter version 2.2.2 at /Users/user/development/flutter
      • Framework revision d79295af24 (4 weeks ago), 2021-06-11 08:56:01 -0700
      • Engine revision 91c9fc8fe0
      • Dart version 2.13.3
  </code></pre>