Как мне справиться с этой ошибкой

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Ошибка
Необработанное исключение типа 'System.FormatException' произошло в mscorlib.dll

Дополнительная информация: строка не была распознана как допустимая Дата-Время. Существует неизвестное слово, начинающееся с индекса 0.


Код:

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 Data_Entry
{
    public partial class mainform : Form

    {
        public mainform()
        {
            InitializeComponent();
        }
       
        Dataaccess dc= new Dataaccess();

        private void groupControl1_Paint(object sender, PaintEventArgs e)
        {

        }
        private void buttonclear_Click(object sender, EventArgs e)
        {
           this.textEditserialno.Text = "";
           this.textEditname.Text = "";
           this.textEditfathername.Text = "";
           comboBoxgender.SelectedIndex = -1;
           this.textEditcnic.Text = "";
           this.textEditmobileno.Text = "";
           this.textEditaddress.Text = "";
           //this.textEditvc.Text = "";
           //this.textEdittehsil.Text = "";
           //this.textEditdistrict.Text = "";
           this.textEditoccupation.Text = "";
        }

        private void Buttonsubmitt_Click(object sender, EventArgs e)
        {
            //try
            //{
                String serialno = textEditserialno.Text.ToString();
                //int serial= Int32.Parse(serialno);
                long serial = Int64.Parse(serialno);
                String name = textEditname.Text.ToString();
                String fathername = textEditfathername.Text.ToString();
                String gender = comboBoxgender.SelectedItem.ToString();
                String nic = textEditcnic.Text.ToString();
                //int cnic = Int32.Parse(nic);
                long cnic = Int64.Parse(nic);
                String mobileno = textEditmobileno.Text.ToString();
                //int mobile = Int32.Parse(mobileno);
                long mobile = Int64.Parse(mobileno);
                DateTime date = DateTime.Parse(dateEditdob.ToString());
                String address = textEditaddress.Text.ToString();
                String vc = textEditvc.Text.ToString();
                String tehsil = textEdittehsil.Text.ToString();
                String district = textEditdistrict.Text.ToString();
                String occupation = textEditoccupation.Text.ToString();

                String q = "Insert into entry values(" + serial + ",'" + name + "','
" + fathername + "','" + gender + "'," + cnic + "," + mobileno + ",'" +date+ "',''" + address + "','" + vc + "','" + tehsil + "','" + district + "','" + occupation + "')";
                SqlCommand sc = new SqlCommand (q,dc.open());
                 sc.ExecuteNonQuery();
                //if (i>=1)
                    MessageBox.Show("Data Entered Successfully : ");
                //else
                //    MessageBox.Show("Data Not Entered ");
//}catch(System.Exception exp){
            //    MessageBox.Show("Error is " + exp.ToString());
            }
            
        }

        
    }

Что я уже пробовал:

Я попробовал, но не нашел ошибки

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const string Query = @"INSERT INTO entry (serial, name, fathername, gender, cnic, mobileno, date, address, vc, tehsil, district, occupation) VALUES (@serial, @name, @fathername, @gender, @cnic, @mobileno, @date, @address, @vc, @tehsil, @district, @occupation)";

using (SqlConnection connection = dc.Open())
using (SqlCommand command = new SqlCommand(Query, connection))
{
    command.Parameters.AddWithValue("@serial", serial);
    command.Parameters.AddWithValue("@name", name);
    command.Parameters.AddWithValue("@fathername", fathername);
    command.Parameters.AddWithValue("@gender", gender);
    command.Parameters.AddWithValue("@cnic", cnic);
    command.Parameters.AddWithValue("@mobileno", mobileno);
    command.Parameters.AddWithValue("@date", date);
    command.Parameters.AddWithValue("@address", address);
    command.Parameters.AddWithValue("@vc", vc);
    command.Parameters.AddWithValue("@tehsil", tehsil);
    command.Parameters.AddWithValue("@district", district);
    command.Parameters.AddWithValue("@occupation", occupation);
    command.ExecuteNonQuery();
}