Object reference not set to an instance of an object.

protected void gvEdit_RowUpdating(object sender, GridViewUpdateEventArgs e)
  {
     byte[] imageData = ((FileUpload)gvEdit.Rows[e.RowIndex].Cells[9].FindControl("FileUpload1")).FileBytes;
      
     string Id = gvEdit.DataKeys[e.RowIndex].Value.ToString();
     int ID = Convert.ToInt32(Id);

     string userName = Page.User.Identity.Name; 

      ShadingAnalysisDataSetTableAdapters.tbl_SiteLayOutUploadTableAdapter sl;
      sl = new ShadingAnalysisDataSetTableAdapters.tbl_SiteLayOutUploadTableAdapter();
      DataTable dt = new DataTable();

      sl.UpdateImageData(DateTime.Now, userName, imageData, ID);

      gvEdit.EditIndex = -1;
      BindData();
        
    }

<asp:GridView ID="gvEdit" runat="server" AutoGenerateColumns="False" AutoGenerateDeleteButton="True" AutoGenerateEditButton="True" DataKeyNames="Id" Width="966px" OnRowCancelingEdit="gvEdit_RowCancelingEdit" OnRowDeleting="gvEdit_RowDeleting" OnRowEditing="gvEdit_RowEditing" OnRowUpdating="gvEdit_RowUpdating" OnRowDataBound="gvEdit_RowDataBound">
<Columns>
<asp:BoundField DataField="Id" HeaderText="Sl No" ReadOnly="True" SortExpression="Id" />
<asp:BoundField DataField="State" HeaderText="State" ReadOnly="True" SortExpression="State" />
<asp:BoundField DataField="District" HeaderText="District" ReadOnly="True" SortExpression="District" />
<asp:BoundField DataField="Cluster" HeaderText="Cluster" ReadOnly="True" SortExpression="Cluster" />
<asp:BoundField DataField="Site_Name" HeaderText="Site Name" ReadOnly="True" SortExpression="Site_Name" />
<asp:BoundField DataField="Site_ID" HeaderText="Site ID" ReadOnly="True" SortExpression="Site_ID" />
<asp:BoundField DataField="Created_Date" HeaderText="Created Date" ReadOnly="True" SortExpression="Created_Date" />
<asp:BoundField DataField="Created_By" HeaderText="Created By" ReadOnly="True" SortExpression="Created_By" />
<asp:BoundField DataField="Version_No" HeaderText="Version No" ReadOnly="True" SortExpression="Version_No" />
<asp:TemplateField HeaderText="Image FIle" SortExpression="ImgData">
 <EditItemTemplate>
   <asp:FileUpload ID="FileUpload2" runat="server" />
 </EditItemTemplate>
</asp:TemplateField>

<asp:TemplateField HeaderText="Image">
 <EditItemTemplate>
   <asp:Image ID="Image1" runat="server" Width="150px" Height="150px"/>
 </EditItemTemplate>
<ItemTemplate>
<asp:Label ID="Label1" runat="server"></asp:Label>
 </ItemTemplate>
</asp:TemplateField>

</Columns>
</asp:GridView>