Не десериализуется json c#

Есть websocket сервер на c# и клиент на python. При отправке json по websocket получаю ошибку десериализации на сервере:

info: Microsoft.Hosting.Lifetime[0]
      Now listening on: https://localhost:8080
info: Microsoft.Hosting.Lifetime[0]
      Now listening on: http://localhost:8000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /home/backend/WebSocket/WebSocket
fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HM0UGBM202QI", Request id "0HM0UGBM202QI:00000001": An unhandled exception was thrown by the application.
System.Text.Json.JsonException: '0x00' is invalid after a single JSON value. Expected end of data. Path: $ | LineNumber: 0 | BytePositionInLine: 98.
 ---> System.Text.Json.JsonReaderException: '0x00' is invalid after a single JSON value. Expected end of data. LineNumber: 0 | BytePositionInLine: 98.
   at System.Text.Json.ThrowHelper.ThrowJsonReaderException(Utf8JsonReader& json, ExceptionResource resource, Byte nextByte, ReadOnlySpan`1 bytes)
   at System.Text.Json.Utf8JsonReader.ConsumeNextToken(Byte marker)
   at System.Text.Json.Utf8JsonReader.ConsumeNextTokenOrRollback(Byte marker)
   at System.Text.Json.Utf8JsonReader.ReadSingleSegment()
   at System.Text.Json.Utf8JsonReader.Read()
   at System.Text.Json.JsonSerializer.ReadCore(JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& readStack)
   --- End of inner exception stack trace ---
   at System.Text.Json.ThrowHelper.ReThrowWithPath(ReadStack& readStack, JsonReaderException ex)
   at System.Text.Json.JsonSerializer.ReadCore(JsonSerializerOptions options, Utf8JsonReader& reader, ReadStack& readStack)
   at System.Text.Json.JsonSerializer.ReadCore(Type returnType, JsonSerializerOptions options, Utf8JsonReader& reader)
   at System.Text.Json.JsonSerializer.ParseCore(ReadOnlySpan`1 utf8Json, Type returnType, JsonSerializerOptions options)
   at System.Text.Json.JsonSerializer.Deserialize[TValue](ReadOnlySpan`1 utf8Json, JsonSerializerOptions options)
   at WebSocket.Middlewares.Pred.Echo(HttpContext context, WebSocket webSocket) in /home/backend/WebSocket/WebSocket/Middlewares/Pred.cs:line 28
   at WebSocket.Startup.<>c.<<Configure>b__1_0>d.MoveNext() in /home/backend/WebSocket/WebSocket/Startup.cs:line 35
--- End of stack trace from previous location where exception was thrown ---
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

Код на c#:

using System;
using System.Net.WebSockets;
using System.Text;
using System.Text.Json;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Http;
using WebSocket.Models;

namespace WebSocket.Middlewares
{
    public static class Pred
    {
        static Encoding _encoding = Encoding.UTF8;
        static RestClient _restClient = new RestClient();

        public static async Task Echo(HttpContext context, System.Net.WebSockets.WebSocket webSocket)
        {
            var buffer = new byte[1024 * 8];
            
            var byteMessage = new byte[0];
            int countMessage = 0;

            WebSocketReceiveResult result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);

            while (!result.CloseStatus.HasValue)
            {
                var msg = JsonSerializer.Deserialize<Message>(buffer);
                
                if (msg.Type == "GetEngines")
                {
                    byteMessage = _encoding.GetBytes(JsonSerializer.Serialize(_restClient.Engines));
                    countMessage = JsonSerializer.Serialize(_restClient.Engines).Length;
                }
                else if (msg.Type == "GetMarkets")
                {
                    await _restClient.GetMarkets(msg.Us);
                    byteMessage = _encoding.GetBytes(JsonSerializer.Serialize(_restClient.Markets));
                    countMessage = JsonSerializer.Serialize(_restClient.Markets).Length;
                }
                else if (msg.Type == "GetBoards")
                {
                    await _restClient.GetBoards(msg.Us);
                    byteMessage = _encoding.GetBytes(JsonSerializer.Serialize(_restClient.Boards));
                    countMessage = JsonSerializer.Serialize(_restClient.Boards).Length;
                }
                else if (msg.Type == "GetSecurities")
                {
                    await _restClient.GetSecurities(msg.Us);
                    byteMessage = _encoding.GetBytes(JsonSerializer.Serialize(_restClient.Securities));
                    countMessage = JsonSerializer.Serialize(_restClient.Securities).Length;
                }
                
                await webSocket.SendAsync(new ArraySegment<byte>(byteMessage, 0, countMessage), result.MessageType, result.EndOfMessage, CancellationToken.None);
                
                result = await webSocket.ReceiveAsync(new ArraySegment<byte>(buffer), CancellationToken.None);
            }
            
            await webSocket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None);
        }
    }
}

Код на python:

class App:
    def __init__(self) -> None:
        self.fragmentation = Fragmentation()

    @staticmethod
    async def main() -> None:
        async with aiohttp.ClientSession() as session:

            async with session.ws_connect('ws://localhost:8000/pred', ssl=False) as ws:
                await ws.send_json({"type": "GetMarkets", "us":
                                    {"engine": "stock", "market": None, "board": None, "security": None}})

                async for msg in ws:
                    if msg.type == aiohttp.WSMsgType.TEXT:
                        if msg.data == 'close cmd':
                            await ws.close()
                            break
                        else:
                            print(msg.data)
                            await ws.send_json({"type": "GetMarkets", "us":
                                {"engine": "stock", "market": None, "board": None, "security": None}})
                    elif msg.type == aiohttp.WSMsgType.ERROR:
                        break


if __name__ == '__main__':
    logging.basicConfig(level=logging.DEBUG)

    app: App = App()
    asyncio.run(app.main())