Error while executing project in Visual Studio

When I run a project in Visual Studio it has the following error:

  

A first chance exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll

Code

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Data.SqlClient;

namespace Logar
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string conexao = "Data Source=(local);Initial Catalog=Cadastro;User ID=sa;Password=m4st3r!";
            SqlConnection add = new SqlConnection(conexao);
            SqlCommand comado = new SqlCommand("select count (*) Usuario where Usuario =@user and Senha=@senha", add);

            comado.Parameters.Add("@user", SqlDbType.VarChar).Value = textBox1.Text;
            comado.Parameters.Add("@senha", SqlDbType.VarChar).Value = textBox2.Text;

            add.Open();
            int i = (int) comado.ExecuteScalar();
            if (i > 0)
            {
                MessageBox.Show("Login e senha encontrado");
            }
            else
            {
                MessageBox.Show("Erro");
            }
            add.Close();
        }
    }
}

What error is this?