Object reference not set to an instance of an object.

Posted on 2013-05-22
Last Modified: 2013-06-03
In button click event, I got this error. I am not sure why.
Object reference not set to an instance of an object.

  Dim filename As String
  filename = Me.FileUpload1.PostedFile.FileName
Question by:VBdotnet2005
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
LVL 23

Expert Comment

by:Ioannis Paraskevopoulos
ID: 39191321

Try the following code:
        filename = CType(Page.FindControl("FileUpload1"), FileUpload).PostedFile.FileName

Open in new window

LVL 13

Accepted Solution

jitendra patil earned 500 total points
ID: 39193921

The problem lies in your aspx code.

You need to add a trigger to your update panel as given below
              <asp:PostBackTrigger ControlID="btnUpload" />

view the complete code here
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" runat="Server">
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        <asp:UpdatePanel ID="UpdatePanel_1" runat="server">
                            Upload File
                            <asp:FileUpload ID="FileUpload1" runat="server" Size="100" />&nbsp;&nbsp;
                            <asp:Button ID="btnUpload" runat="server" Text="Upload" />
                            &nbsp;<br />
                            <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" CellPadding="4"
                                DataKeyNames="ID" DataSourceID="SqlDataSource1" ForeColor="#333333" GridLines="Vertical"
                                HorizontalAlign="Center" Width="100%">
                                <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
                                            <asp:CheckBox ID="CheckBox1" runat="server" />
                                    <asp:BoundField DataField="CustomerID" HeaderText="CustomerID" SortExpression="CustomerID" />
                                    <asp:TemplateField HeaderText="filename">
                                            <asp:HyperLink ID="HyperLink1" runat="server" NavigateUrl='<%# string.format("test.aspx?={0}", Databinder.Eval(container.Dataitem, "filename")) %>'
                                                Text='<%# Databinder.Eval(container.dataitem, "filename") %>'></asp:HyperLink>
                                    <asp:BoundField DataField="ID" HeaderText="ID" SortExpression="ID" Visible="false" />
                                    <asp:BoundField DataField="map_client" HeaderStyle-HorizontalAlign="Center" HeaderText="Map Columns"
                                        ItemStyle-HorizontalAlign="Center" Visible="true" />
                                <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
                                <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
                                <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
                                <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" HorizontalAlign="Left" />
                                <EditRowStyle BackColor="#999999" />
                                <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
                                    <table bgcolor="#5D7B9D" style="width: 100%; border-style: solid; border-width: 1px">
                                            <td style="color: #FFFFFF">
                                                    No Data Found</center>
                            <asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:myconConnectionString %>"
                                ProviderName="System.Data.SqlClient" SelectCommand="mysp"
                            <asp:Button ID="Button1" runat="server" Text="Button" Visible="False" />
                            <asp:LinkButton ID="LinkButton1" runat="server">Clear</asp:LinkButton>
                            <br />
              <asp:PostBackTrigger ControlID="btnUpload" />
        <asp:UpdateProgress ID="UpdateProgress2" runat="server" AssociatedUpdatePanelID="UpdatePanel_1">
                <div id="progress" align="center" valign="middle" runat="server" style="border-width: thin;
                    border-color: black; position: absolute; left: 0%; top: 4%; visibility: visible;
                    vertical-align: middle; background-color: White; z-index: 40;">
                    <table width="1054px" height="510px">
                                Please wait...<br />
                                <br />
                                <img src="image/test.gif" />

Open in new window

your backend code is working fine.

once you add a trigger to your  update panel you will get the desired result without performing a full postback, it will be a partial post back and you update panel will know that this button needs an action to be done.

hope this helps.

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In .NET 2.0, Microsoft introduced the Web Site.  This was the default way to create a web Project in Visual Studio 2005.  In Visual Studio 2008, the Web Application has been restored as the default web Project in Visual Studio/.NET 3.x The Web Si…
IntroductionWhile developing web applications, a single page might contain many regions and each region might contain many number of controls with the capability to perform  postback. Many times you might need to perform some action on an ASP.NET po…
In this video, viewers will be given step by step instructions on adjusting mouse, pointer and cursor visibility in Microsoft Windows 10. The video seeks to educate those who are struggling with the new Windows 10 Graphical User Interface. Change Cu…
In this video, viewers are given an introduction to using the Windows 10 Snipping Tool, how to quickly locate it when it's needed and also how make it always available with a single click of a mouse button, by pinning it to the Desktop Task Bar. Int…

734 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question