C# Crystal Report WinForm如何修复错误对象引用未设置为对象实例？

Windows窗体C上的crystal report 2008

错误：对象引用未设置为对象的实例

如何修复它

string appConn = ConfigurationManager.ConnectionStrings["connDB"].ConnectionString;

private void button5_Click(object sender, EventArgs e)
        {
            SqlConnection objConn = new SqlConnection();
            SqlCommand objCmd = new SqlCommand();
            SqlDataAdapter dtAdapter = new SqlDataAdapter();

            DataSet ds = new DataSet();
            DataTable dt;
            string strSQL;

            strSQL = "SELECT * FROM filesTA WHERE ChkDate = '" + dateTimePicker2.Value.ToString("yyyy-MM-dd") + "'";

            objConn.ConnectionString = appConn;
            var _with1 = objCmd;
            _with1.Connection = objConn;
            _with1.CommandText = strSQL;
            _with1.CommandType = CommandType.Text;
            dtAdapter.SelectCommand = objCmd;

            dtAdapter.Fill(ds, "myDataTable");
            dt = ds.Tables[0];

            dtAdapter = null;
            objConn.Close();
            objConn = null;

            ReportDocument rpt = new ReportDocument();
                   rpt.Load(System.Web.HttpContext.Current.Server.MapPath("Report\\CrystalReport1.rpt")); <<< Error
            rpt.SetDataSource(dt);
            this.crystalReportViewer1.ReportSource = rpt;
            this.crystalReportViewer1.Refresh();
        }

---

请帮帮我。谢谢你抽出时间

好吧，我建议您更仔细地查看堆栈跟踪。但是，我猜测System.Web.HttpContext.Current为空。许多人没有意识到这可能是空的，所以当您尝试引用它的服务器属性时，您会得到一个空引用异常