Java.Net.SocketException Error: Socket closed in System.net.Http httpClient, occurs only when sending files larger than 50kbs - http

Question

I am making a program in xamarin, which uses http requests to get data from an API made in net.core 2.0, but some requests (most of them actually) culminate in the following error:
System.AggregateException: One or more errors occurred. ---> Java.Net.SocketException: Socket closed
at Java.Interop.JniEnvironment+InstanceMethods.CallIntMethod (Java.Interop.JniObjectReference instance, Java.Interop.JniMethodInfo method, Java.Interop.JniArgumentValue* args) [0x00069] in <286213b9e14c442ba8d8d94cc9dbec8e>:0
at Java.Interop.JniPeerMembers+JniInstanceMethods.InvokeVirtualInt32Method (System.String encodedMember, Java.Interop.IJavaPeerable self, Java.Interop.JniArgumentValue* parameters) [0x0002a] in <286213b9e14c442ba8d8d94cc9dbec8e>:0
at Java.Net.HttpURLConnection.get_ResponseCode () [0x0000a] in <b781ed64f1d743e7881ac038e0fbdf85>:0
at Xamarin.Android.Net.AndroidClientHandler+<>c__DisplayClass45_0.<DoProcessRequest>b__1 () [0x00000] in <b781ed64f1d743e7881ac038e0fbdf85>:0
at System.Threading.Tasks.Task`1[TResult].InnerInvoke () [0x0000f] in <d4a23bbd2f544c30a48c44dd622ce09f>:0
at System.Threading.Tasks.Task.Execute () [0x00000] in <d4a23bbd2f544c30a48c44dd622ce09f>:0
--- End of stack trace from previous location where exception was thrown ---
at Xamarin.Android.Net.AndroidClientHandler+<DoProcessRequest>d__45.MoveNext () [0x0036c] in <b781ed64f1d743e7881ac038e0fbdf85>:0
--- End of stack trace from previous location where exception was thrown ---
at Xamarin.Android.Net.AndroidClientHandler+<SendAsync>d__40.MoveNext () [0x00230] in <b781ed64f1d743e7881ac038e0fbdf85>:0
--- End of stack trace from previous location where exception was thrown ---
at System.Net.Http.HttpClient+<SendAsyncWorker>d__49.MoveNext () [0x000ca] in <25ebe1083eaf4329b5adfdd5bbb7aa57>:0
--- End of inner exception stack trace ---
at System.Threading.Tasks.Task.ThrowIfExceptional (System.Boolean includeTaskCanceledExceptions) [0x00011] in <d4a23bbd2f544c30a48c44dd622ce09f>:0
at System.Threading.Tasks.Task`1[TResult].GetResultCore (System.Boolean waitCompletionNotification) [0x0002b] in <d4a23bbd2f544c30a48c44dd622ce09f>:0
at System.Threading.Tasks.Task`1[TResult].get_Result () [0x0000f] in <d4a23bbd2f544c30a48c44dd622ce09f>:0
at FonoApp.Services.DataService.SendImageAsync (System.String token, FonoApp.Model.Imagem imagem) [0x00059] in C:\Projetos Sorri\FonoApp\AppTeste\AppTeste\Services\DataService.cs:154
--- End of inner exception stack trace ---}
This error occurs in this code snippet:
public async Task<String> SendImage(string token, Imagem imagem)
{
string baseAddress = #"http://192.168.0.4:5000/" + VersaoApi + #"/Imagem/";
var json = JsonConvert.SerializeObject(imagem);
var contentString = new StringContent(json, Encoding.UTF8, "application/json");
client.DefaultRequestHeaders.Authorization =
new AuthenticationHeaderValue("Bearer", token);
try
{
HttpResponseMessage tokenResponse = client.PostAsync(baseAddress, contentString).Result;//Erro ocorre nesta linha
var jsonContent = tokenResponse.Content.ReadAsStringAsync().Result;
return jsonContent;
}
catch (Exception e)
{
return e.InnerException.Message.ToString();
}
}
From what I researched, and discovered from this error, means that the connection is being closed either by the server or by the client, but I can't even know who closes the connection suddenly let alone prevent this / exception error, I don't know if it matters but I am testing the app on an android 4.2-API 17 tablet. Thanks in advance for any guidance on this as I am still learning how to program in C #.
one thing I forgot to say before was that Postman API requests work without problems
I noticed something interesting the error I get only occurs when trying to send images larger than 100 kb by http request, how can I increase the send and receive weight limit on my server?

Answer 1

Firstly, you need to use await instead of Result() to make this method async:
var jsonContent = await tokenResponse.Content.ReadAsStringAsync();
And yes, this exception occurs when internet connection is lost. You can do these things to make your app more usable:
Display a warning message in try-catch block
Check internet connection by using Xamarin.Essentials.Connectivity plugin
Set a timeout for your HttpClient object and catch the TimeoutException to display proper message