Invalid postback or callback argument. How to solve this exception?

Question

I am getting this exception while uploading a file.

Invalid postback or callback argument. Event validation is enabled using in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation

Code behind:

public partial class LBMIS1New : System.Web.UI.Page
{
    protected void Upload(object sender, EventArgs e)
    {
        //Upload and save the file
        string excelPath = Server.MapPath("~/Doc/") + Path.GetFileName(FileUpload1.PostedFile.FileName);
        FileUpload1.SaveAs(excelPath);

        string conString = string.Empty;
        string extension = Path.GetExtension(FileUpload1.PostedFile.FileName);
        switch (extension)
        {
            case ".xls": //Excel 97-03
                conString = ConfigurationManager.ConnectionStrings["Excel03ConString"].ConnectionString;
                break;
            case ".xlsx": //Excel 07 or higher
                conString = ConfigurationManager.ConnectionStrings["Excel07+ConString"].ConnectionString;
                break;
        }
        conString = string.Format(conString, excelPath);
        using (OleDbConnection excel_con = new OleDbConnection(conString))
        {
            excel_con.Open();
            string sheet1 = excel_con.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null).Rows[0]["TABLE_NAME"].ToString();
            DataTable dtExcelData = new DataTable();

            //[OPTIONAL]: It is recommended as otherwise the data will be considered as String by default.
            dtExcelData.Columns.AddRange(new DataColumn[7] {
                new DataColumn("Id", typeof(int)),
                new DataColumn("Banks", typeof(string)),
                new DataColumn("Crop Loan", typeof(int)),
                new DataColumn("Water Resources", typeof(decimal)),
                new DataColumn("Farm Mechanisation", typeof(int)),
                new DataColumn("Plantation & Horticulture",
                typeof(decimal)),
                new DataColumn("Forestry & Wasteland Dev.", typeof(int))
            });

            using (OleDbDataAdapter oda = new OleDbDataAdapter("SELECT * FROM [" + sheet1 + "A2:F]", excel_con))
            {
                oda.Fill(dtExcelData);
            }
            excel_con.Close();

            string consString = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;
            using (SqlConnection con = new SqlConnection(consString))
            {
                using (SqlBulkCopy sqlBulkCopy = new SqlBulkCopy(con))
                {
                    //Set the database table name
                    sqlBulkCopy.DestinationTableName = "dbo.TestLDM";

                    //[OPTIONAL]: Map the Excel columns with that of the database table
                    sqlBulkCopy.ColumnMappings.Add("Id", "LDM_LBSMI1ID");
                    sqlBulkCopy.ColumnMappings.Add("Banks", "BankName");
                    sqlBulkCopy.ColumnMappings.Add("Crop Loan", "PCropLoanNo");
                    sqlBulkCopy.ColumnMappings.Add("Water Resources", "PCropLoanAmt");
                    sqlBulkCopy.ColumnMappings.Add("Farm Mechanisation", "PTermLoanWaterRNo");
                    sqlBulkCopy.ColumnMappings.Add("Plantation & Horticulture", "PTermLoanWaterRAmt");
                    sqlBulkCopy.ColumnMappings.Add("Forestry & Wasteland Dev.", "PTermLoanFarmMechanisationNo");
                    con.Open();
                    sqlBulkCopy.WriteToServer(dtExcelData);
                    con.Close();
                }
            }
        }
    }

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            BindGridview();
        }
    }

    protected void BindGridview()
    {
        string conString = ConfigurationManager.ConnectionStrings["conn"].ConnectionString;
        DataSet ds = new DataSet();
        using (SqlConnection con = new SqlConnection(conString))
        {
            con.Open();
            SqlCommand cmd = new SqlCommand("select * from dbo.TestLDM", con);
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            da.Fill(ds);
            con.Close();
            gvDetails.DataSource = ds;
            gvDetails.DataBind();
        }
    }

    protected void gvDetails_PageIndexChanging(object sender, GridViewPageEventArgs e)
    {
        gvDetails.PageIndex = e.NewPageIndex;
        BindGridview();
    }
}

Answer 1

On your aspx form, above your html code turn off the EventValidation it will be solved.

EnableEventValidation="false"