Not getting posted file in asp.net 3.5. FileUpload control - file-upload

Question

this my code in my user control's designer file
<%# Control Language="C#" AutoEventWireup="true" CodeBehind="ucImageList.ascx.cs"
Inherits="Pariwaar.UserControl.ucImageList" %>
<asp:ScriptManagerProxy ID="ajaxScriptManagerProxy" runat="server">
</asp:ScriptManagerProxy>
<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Always">
<ContentTemplate>
<asp:HiddenField ID="hidUserId" runat="server" />
<asp:HiddenField ID="hidAlbumId" runat="server" />
<table>
<tr>
<td>
<asp:FileUpload ID="fvUploadFile" runat="server" EnableViewState="true" />
<asp:LinkButton ID="AddImageInfoButton" CssClass="blueLink" runat="server" Text="Upload"
OnClick="AddImageInfoButton_Click"></asp:LinkButton>
</td>
</tr>
<tr>
<td>
<asp:DataList ID="DtLstImageList" runat="server" DataSourceID="odsImageList" OnItemCommand="DtLstImageList_ItemCommand"
EnableTheming="true" RepeatColumns="4" RepeatDirection="Horizontal">
<ItemTemplate>
<ul>
<li style="display: block; text-align: center;">
<asp:ImageButton ID="ImgBtnImagePath" runat="server" ImageUrl='<%# DataBinder.Eval(Container.DataItem, "ImagePath")%>'
ImageAlign="Middle" Width="100" Height="100" CommandName="ViewImage" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "ImageId")%>' />
</li>
<li style="display: block;">
<asp:Button ID="UpdateCoverPageImage" runat="server" Text="Set as Cover Page" CssClass="inputButtonWithoutpadding"
CommandName="SetAsCoverPage" CommandArgument='<%# DataBinder.Eval(Container.DataItem, "ImageId")%>' />
</li>
</ul>
</ItemTemplate>
</asp:DataList>
</td>
</tr>
</table>
</ContentTemplate>
</asp:UpdatePanel>
<asp:ObjectDataSource ID="odsImageList" runat="server" SelectMethod="GetImageInfo"
TypeName="Pariwaar.Controller.GallaryHandler" DeleteMethod="DeleteImageInfo">
<DeleteParameters>
<asp:Parameter Name="ImageId" Type="Int64" />
</DeleteParameters>
<SelectParameters>
<asp:Parameter DefaultValue="0" Name="ImageId" Type="Int64" />
<asp:ControlParameter ControlID="hidAlbumId" Name="AlbumId" PropertyName="Value"
Type="Int64" DefaultValue="0" />
</SelectParameters>
</asp:ObjectDataSource>
i am not getting Fiepath/name and Fileupload controls' posted file property is null
i am checking fvFileUpload.Postedfile in click event of AddImageInfoButton
can anybody please tell me what i am doing wrong in this code...
-thanks in advance

Answer 1

File uploads are not supported in async postbacks, such as when you use the UpdatePanel. Read this blog post for more details.
Here are two proposed workarounds:
Have a dedicated "Upload" button that does a regular postback instead of an async postback. You can achieve this using several techniques: Have the button be outside all UpdatePanels; have the button be the target of an UpdatePanel's PostBackTrigger; or call ScriptManager.RegisterPostBackControl() on it.
Have a dedicated file upload page that doesn't have any UpdatePanels. Many web sites already do this anyway.