System.Runtime.Serialization.SerializationException: The input stream is not a valid binary format. The starting contents (in bytes) are:

To begin with, I'm a student, don't scold me too much for my code, I'm trying to get better. I will accept any criticism about the code, it helps to get better)

The crux of my problem: when the server is disconnected, I send a command to it, process it, and send a response from the server stating that it has completed its work, in my second project (client) I receive a message and process it, and sometimes it is processed, and sometimes it happens the problem is that I just get an exception. And it comes out of nothing, the server shutdown function works, I have to display a MessageBox, and it immediately switches me to another function and receives an exception for converting a byte to an object (the function works correctly, all other commands work without problems). I have already climbed all the Internet resources, nothing helps.

Where does the exception occur

 public Object ByteArrayToObject(byte[] arrBytes)
        {
            using (var memStream = new MemoryStream())
            {
                var binForm = new BinaryFormatter();
                memStream.Write(arrBytes, 0, arrBytes.Length);
                memStream.Seek(0, SeekOrigin.Begin);
                object obj = binForm.Deserialize(memStream);***//ERROR HERE  System.Runtime.Serialization.SerializationException: The input stream is not a valid binary format. The starting contents (in bytes) are:***
                return obj;
            }
        }

The start of an exception occurs in this function after receiving a message from the server before or during the display of the MessageBox at this moment it switches me to this function and catches an exception

private  void DisconnectServer()
        {
            try
            {
                string theMessage = "Клиент выполнил дисконнект"; 
                byte[] msg = Encoding.Default.GetBytes(theMessage); 
                int bytesSent = sock.Send(msg);
                byte[] bytes = new byte[1024];
                int bytesRec = sock.Receive(bytes);
                string msgserv = Encoding.Default.GetString(bytes, 0, bytesRec);
                //MessageBox.Show("Сервер (" + sock.RemoteEndPoint.ToString() + ") ответил: " + msgserv);
                sock.Shutdown(SocketShutdown.Both); 
                sock.Close();

            }
            catch (Exception ex)
            {
                MessageBox.Show("Клиент: " + ex.Message);
            }
        }

The moment the server message is sent to the client about the disconnection and after which an error occurs

 Console.ForegroundColor = ConsoleColor.Red;
                            Console.WriteLine(client + ":" + data);
                            Console.ResetColor();
                            string theReply = "Сервер остановлен";
                            byte[] msg = Encoding.Default.GetBytes(theReply);
                            handler.Send(msg);
                            choice = 0;
                            handler.Shutdown(SocketShutdown.Both);
                            handler.Close();
                            break;