Read a csv file using 2D array

Question

I want to read a csv file using 2D array, there will be an exception error, please help me

private void button1_Click(object sender, EventArgs e)
{
    //new a excel
    Microsoft.Office.Interop.Excel.Application excel = new Microsoft.Office.Interop.Excel.Application();
    excel.Application.Workbooks.Add(true);
    if (openFileDialog1.ShowDialog() ==System.Windows.Forms.DialogResult.OK)
    {
        string theFile = openFileDialog1.FileName;
        Encoding enc = Encoding.GetEncoding("UTF-8");
        //var readText1 = File.ReadAllLines(theFile);
        var readText1 = System.IO.File.ReadAllLines(theFile);
        var readText = File.ReadAllLines(theFile).Select(l =>
             l.Split(',').ToArray()).ToArray();
        var rows = readText1.Count();
        //Number of rows columns
        var columns = readText1[0].Split(',').Count();
        //var columns = readText.Count();
        excel.Visible = true;
        for (int i = 0; i < rows; i++)
        {
            for (int j = 0; j < columns; j++)
            {
                excel.Cells[i + 1, j + 1] = readText[j][i];
                //Console.WriteLine();
            }
        }
    }
}