SqlBulkInserT- Import Excel worksheet

I have an application in dotnet to import spreadsheet, however I do not know why I am not able to insert the information into the database. My code is below.

using System;
using System.Collections.Generic;
using System.Data;
using System.Data.OleDb;
using System.IO;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;

 protected void importar_Click(object sender, EventArgs e)
{
    //Carregar e salvar o arquivo
    string excelPath = Server.MapPath("~/Files/") + Path.GetFileName(selecionarArquivo.PostedFile.FileName);
    string conString = string.Empty;
    string extension = Path.GetExtension(selecionarArquivo.PostedFile.FileName);

    //Validação
    //Valida a extensão do arquivo:
    if (Path.GetExtension(selecionarArquivo.FileName) != ".xlsx" && Path.GetExtension(selecionarArquivo.FileName) != ".xls")
    {

    }
    else
    {
        ClientScript.RegisterStartupScript(typeof(string), "Erro", "<script>alert('Somente arquivos em excel')</script>");
    }

    conString = string.Format(conString, excelPath);
    using (OleDbConnection excel_con = new OleDbConnection(conString))
    {
        excel_con.Open(); //->>>> Aqui está dando um erro estranho a propriedade connectionstring não foi inicializada.
        string sheet1 = excel_con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null).Rows[6]["TABLE_NAME"].ToString();
        DataTable dtExcelData = new DataTable();

        //[OPTIONAL]: Recomenda-se, caso contrário, os dados serão considerados como String por padrão.
        dtExcelData.Columns.AddRange(new DataColumn[] { new DataColumn("Id", typeof(int)), // [] passar o valor do campo da tabela do bd

         // Aqui colocarei o campo da planilha de excel
        new DataColumn("Data de Requisição do Pgto", typeof(DateTime)),
        new DataColumn("NUMERO PROCESSO ANTERIOR",typeof(Int32)),
        new DataColumn("NUMERO JUDICIAL", typeof(Int32)),
        new DataColumn("COMARCA", typeof(string)),
        new DataColumn("VARA", typeof(string)),
        new DataColumn("NOME", typeof(string)),
        new DataColumn("CPF", typeof(Int16)),
        new DataColumn("DEENDERECO", typeof(string)),
        new DataColumn("NUENDERECO", typeof(string)),
        new DataColumn("DECOMPLEMENTO", typeof(string)),
        new DataColumn("DEBAIRRO", typeof(string)),
        new DataColumn("NUCEP", typeof(Int16)),
        new DataColumn("NMMUNICIPIO", typeof(string)),
        new DataColumn("BRUTO", typeof(decimal)),
        new DataColumn("IRPF", typeof(decimal)),
        new DataColumn("Nº SEP", typeof(Int16)),
        new DataColumn("DATA SEP", typeof(DateTime)),
        new DataColumn("DATA DE RECEBIMENTO NA ORIGEM", typeof(DateTime)),
        });

        using (OleDbDataAdapter oda = new OleDbDataAdapter("SELECT * FROM sdpj_import_processo", excel_con))
        {
            oda.Fill(dtExcelData);
        }
        excel_con.Close();

        string consString = ConfigurationManager.ConnectionStrings["constr"].ConnectionString;
        using (SqlConnection con = new SqlConnection(consString))
        {
            using (SqlBulkCopy sqlBulkCopy = new SqlBulkCopy(con))
            {
                //Define o nome da tabela
                sqlBulkCopy.DestinationTableName = "@sdpj_import_processo";
                //[OPTIONAL]: Mapeie as colunas do Excel com a da tabela do banco de dados 
                sqlBulkCopy.ColumnMappings.Add("Data de Requisição Pgto", "DAT_REQ_PGTO");
                sqlBulkCopy.ColumnMappings.Add("NUMERO PROCESSO ANTERIOR", "NUM_PROC_ANTERIOR");
                sqlBulkCopy.ColumnMappings.Add("NUMERO JUDICIAL", "NUM_PROC_JUDICIAL");
                sqlBulkCopy.ColumnMappings.Add("COMARCA", "DSC_COMARCA");
                sqlBulkCopy.ColumnMappings.Add("VARA", "NUM_VARA");
                sqlBulkCopy.ColumnMappings.Add("VARANOME", "NME_VARA");
                sqlBulkCopy.ColumnMappings.Add("NOME", "NME_INTERESSADO");
                sqlBulkCopy.ColumnMappings.Add("CPF", "CPF_CNPJ_INTERESSADO");
                sqlBulkCopy.ColumnMappings.Add("DEENDERECO", "DSC_ENDERECO");
                sqlBulkCopy.ColumnMappings.Add("NUENDERECO", "NUM_ENDERECO");
                sqlBulkCopy.ColumnMappings.Add("NMMUNICIPIO", "NME_MUNICIPIO");
                sqlBulkCopy.ColumnMappings.Add("DECOMPLEMENTO", "DSC_DECOMPLEMENTO");
                sqlBulkCopy.ColumnMappings.Add("DEBAIRRO", "NME_BAIRRO");
                sqlBulkCopy.ColumnMappings.Add("NUCEP", "NUM_CEP");
                sqlBulkCopy.ColumnMappings.Add("NMMUNICIPIO", "NME_MUNICIPIO");
                sqlBulkCopy.ColumnMappings.Add("BRUTO", "VLR_BRUTO");
                sqlBulkCopy.ColumnMappings.Add("IRPF", "VLR_IR");
                sqlBulkCopy.ColumnMappings.Add("LIQUIDO", "VLR_LIQUIDO");
                sqlBulkCopy.ColumnMappings.Add("Nº SEP", "COD_SEP");
                sqlBulkCopy.ColumnMappings.Add("DATA SEP", "DAT_SEP");
                sqlBulkCopy.ColumnMappings.Add("DATA DE RECEBIMENTO NA ORIGEM", "DAT_RECEB_ORIGEM");
                con.Open();
                sqlBulkCopy.WriteToServer(dtExcelData);
                con.Close();
            }
        }
    }
}