ASP.NET 'GridView' does not contain a definition for 'VirtualItemCount'

Question

I'm trying to use property VirtualItemCount for custom paging in ASP.NET web Forms GridView, it gives me this error

Severity    Code    Description Project File    Line    Suppression State
Error   CS1061  'GridView' does not contain a definition for 'VirtualItemCount' and no extension method 'VirtualItemCount' accepting a first argument of type 'GridView' could be found (are you missing a using directive or an assembly reference?)   dms D:\project\Screen\ToDoList.aspx.cs  100 Active

when I create new project its works fine but in my current project it appear like its not defined , I search a lot with no case similar to mine.

Do I need to add certain assembly reference or missing settings?

<asp:GridView ID="GridView1" runat="server" CssClass="Grid"
    PageSize="10" 
    AllowPaging="true"
    AutoGenerateColumns="false" OnPageIndexChanging="GridView1_PageIndexChanging">
    <AlternatingRowStyle />
    <Columns>
        <asp:BoundField DataField="Name" HeaderText="Name" />
        <asp:BoundField DataField="Date" HeaderText="Date" />
        <asp:TemplateField>
            <ItemTemplate>
                <input type="button" value="Edit" class="button" />
                <input type="button" value="delete" class="button" />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

It appears like this

These are my settings

Answer 1

我只需转到“ Properties -> Application然后将Target Framework从.NET Framework 4更改为.NET Framework 4.5 ，即可使用