Why doesn't MySql authorization work in C# and WPF?

Question

MySQL

Hello. I've been sitting for 5 hours and I don't understand why mysql authorization code doesn't work for me. I looked at the guides, nothing helped. So here is the code

using System;
using System.Windows;
using MySql.Data.MySqlClient;

namespace GoodWork
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow
    {
        public Manager _m;
        private MySqlConnection connection;
        public MainWindow()
        {
            InitializeComponent();
        }

        private void ExitClick(object sender, System.Windows.RoutedEventArgs e)
        {
            Close();
        }

        private void Submit(object sender, System.Windows.RoutedEventArgs e)
        {
            string loginL = Login.Text;
            string passwordD = Password.Text;
            string connStr = "server=localhost;user=mysql;database=users;password=mysql;";
            connection = new MySqlConnection(connStr);

            try
            {
                connection.Open();
                MySqlCommand cmd = new MySqlCommand("SELECT * FROM user WHERE login='" + loginL + "' AND password='" + passwordD + "'", connection);
                MySqlDataReader dr = cmd.ExecuteReader();
                if (dr.Read())
                {
                    _m.GetUser = loginL;
                    _m.GetPassword = passwordD;
                    MessageBox.Show("OK");
                }
                else
                {
                    MessageBox.Show("Eror " + loginL + " LLLL " + passwordD);
                }
            }
            catch(Exception ex)
            {
                MessageBox.Show(ex.ToString());
            }


            connection.Close();
        }
    }
}

but the error itself

Thanks for the answer!