Error 401 'INVALID_KEY_TYPE' con FireBase y c#

Question

I am implementing c # with FireBase, it sends me error 401 'INVALID_KEY_TYPE'

enter code here

private static Uri FireBasePushNotificationsURL = new Uri("https://fcm.googleapis.com/fcm/send"); private static string ServerKey = "AIzaSyA9fL8lPyxcrngIDDsDeUbq9sPTkavXXXX";

    public static async Task<bool> SendPushNotification(string deviceTokens, string title, string body, object data)
    {
        bool sent = false;

        if (deviceTokens.Count() > 0)
        {
            //Object creation

            var messageInformation = new 
            {
                to = "fZ0EyxU-tsk:APA91bE3-qo4DwL9phteDJC8pG6iLdr-YSSl-N_2SJne3U6eyUhmEuZNQhJi0YM-XXXXXX",
                priority = "high",
                content_available = true,
                notification = new
                {
                    body = "Test",
                    title = "Test miguel",
                    badge = 1
                },
            };

            //Object to JSON STRUCTURE => using Newtonsoft.Json;
            string jsonMessage = JsonConvert.SerializeObject(messageInformation);

            //Create request to Firebase API
            var request = new HttpRequestMessage(HttpMethod.Post, FireBasePushNotificationsURL);

            request.Headers.TryAddWithoutValidation("Authorization", "key=" + ServerKey);
            request.Content = new StringContent(jsonMessage, Encoding.UTF8, "application/json");

            HttpResponseMessage result;
            using (var client = new HttpClient())
            {
                result = await client.SendAsync(request);
                sent = sent && result.IsSuccessStatusCode;
            }
        }

        return sent;

    }

Answer 1

I have the same problem. The problem is that you take the wrong server key. The right firebase server key is Project > Settings > Cloud Messaging > Server Key