Error: Both DataSource and DataSourceID are defined on GridView1 Remove one definition in ASP.Net

Hi, I hope you are in a great day!.

Im new in asp.net and follow the instruction in this link https://www.aspsnippets.com/Articles/Search-records-in-GridView-and-highlight-results-in-ASPNet-using-C-and-VBNet.aspx

I changed the "constr" into "Server=DESKTOP-C6IEOUN\SQLEXPRESS;database =TestPhilSoft; Integrated Security=True" and I got an error saying "Object reference not set to an instance of an object." How can I fix it? 

Any response is much appreciated. Thanks a lot!

Imports System.Data
Imports System.Data.SqlClient
Imports System.Configuration
Imports System.Text.RegularExpressions
Public Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        If Not IsPostBack Then
            Me.BindGrid()
        End If
    End Sub

    Protected Sub txtSearch_TextChanged(sender As Object, e As EventArgs) Handles txtSearch.TextChanged

    End Sub

    Protected Sub btnSearch_Click(sender As Object, e As EventArgs) Handles btnSearch.Click
        If txtSearch.Text = "" Then
            MsgBox("Please Type Name", vbInformation, "Empty Filed!")
        End If

    End Sub
    Protected Sub Search(sender As Object, e As EventArgs)
        Me.BindGrid()
    End Sub

    Private Sub BindGrid()
        Dim constr As String = ConfigurationManager.ConnectionStrings("Server=DESKTOP-C6IEOUN\SQLEXPRESS;database =TestPhilSoft; Integrated Security=True").ConnectionString
        Using con As New SqlConnection(constr)
            Using cmd As New SqlCommand()
                cmd.CommandText = "SELECT Name FROM tblInformation WHERE Name LIKE '%' + @Name + '%'"
                cmd.Connection = con
                cmd.Parameters.AddWithValue("@Name", txtSearch.Text.Trim())
                Dim dt As New DataTable()
                Using sda As New SqlDataAdapter(cmd)
                    sda.Fill(dt)
                    GridView1.DataSource = dt
                    GridView1.DataBind()
                End Using
            End Using
        End Using
    End Sub

    Protected Sub OnPageIndexChanging(sender As Object, e As GridViewPageEventArgs)
        GridView1.PageIndex = e.NewPageIndex
        Me.BindGrid()
    End Sub

    Protected Sub OnRowDataBound(sender As Object, e As GridViewRowEventArgs)
        If e.Row.RowType = DataControlRowType.DataRow Then
            e.Row.Cells(0).Text = Regex.Replace(e.Row.Cells(0).Text, txtSearch.Text.Trim(),
                Function(match As Match) String.Format("<span style = 'background-color:#D9EDF7'>{0}</span>", match.Value),
                            RegexOptions.IgnoreCase)
        End If
    End Sub
End Class