The type initializer for 'IMAGE.Form1' threw an exception.

program.csnamespace IMAGE
{
    static class Program
    {
        /// <summary>
        /// The main entry point for the application.
        /// </summary>
        [STAThread]
        static void Main()
        {
            Application.EnableVisualStyles();
            Application.SetCompatibleTextRenderingDefault(false);
            Application.Run(new Form1());// error coming here.
        }
    }
}

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

namespace IMAGE
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        static string cnstr = ConfigurationSettings.AppSettings["list"];
        static SqlConnection con = new SqlConnection(cnstr);
        private void button1_Click(object sender, EventArgs e)
        {
            OpenFileDialog open = new OpenFileDialog();
            // image filters
            open.Filter = "Image Files(*.jpg; *.jpeg; *.gif; *.bmp)|*.jpg; *.jpeg; *.gif; *.bmp";
            if (open.ShowDialog() == DialogResult.OK)
            {
                // display image in picture box
                pictureBox1.Image = new Bitmap(open.FileName);
                // image file path
                txtimg.Text = open.FileName;
            }



        }

        private void button2_Click(object sender, EventArgs e)
        {
            SqlCommand cmd = new SqlCommand("men_in");
            cmd.Parameters.AddWithValue("@sl_no", txtslno.Text);
            cmd.Parameters.AddWithValue("@car_name", txtcar.Text);
            cmd.Parameters.AddWithValue("@Date_service_given", dateTimePicker1.Value);
            cmd.Parameters.AddWithValue("@Date_completed", dateTimePicker2.Value);
            cmd.Parameters.AddWithValue("@cost", txtcost.Text);
            cmd.Parameters.AddWithValue("@car_image", txtimg.Text);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataSet ds = new DataSet();
            da.Fill(ds, "service");
        }

       
    }
}