Someone can explain this error?
Error Creating Control - head Object reference not set to an instance of an object.
<%@ Page Title="" Language="C#" MasterPageFile="~/Controls/Master1.Master"
AutoEventWireup="true" CodeBehind="GrupoUsuario.aspx.cs" Inherits="GrupoUsuario" %>
<asp:Content ID="Content1" runat="server" contentplaceholderid="head">
</asp:Content>
I Think this is a bug of visual studio 2010 in design view. I'not using any event to manipulate session object in the method OnInt(). The "PlaceHolderTopo" is an placeholder in the web user control Topo.ascx. It's work normaly. I Don't have any code inside the content place holder in the page tha inherits from the master page and get this error.
Below is the code of the masterpage:
<%@ Master Language="C#" AutoEventWireup="true" CodeBehind="PrincipalSeguranca.Master.cs" Inherits="PrincipalSeguranca" %>
<%@ Register Src="Topo.ascx" TagName="Topo" TagPrefix="uc1" %>
<%@ Register src="MenuAdmin.ascx" TagName="MenuAdmin" TagPrefix="uc2" %>
<%@ Register src="Rodape.ascx" tagname="Rodape" tagprefix="uc3" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<title>Sistema</title>
<script language="jscript" type="text/javascript" src="Scripts/Geral.js"></script>
<link rel="shortcut icon" href="../layout/ico/favicon.ico" type="image/x-icon" />
<link rel="stylesheet" href="../layout/css/styles.css" type="text/css" />
<link href="../layout/css/menu_tabbed.css" rel="stylesheet" type="text/css" />
<link rel="stylesheet" href="../layout/css/contents.css" type="text/css" />
</head>
<body>
<form id="form1" ClientInstanceName="form1" runat="server">
<uc1:Topo ID="Topo1" runat="server" />
<div id="corpo">
<asp:ContentPlaceHolder ID="head" runat="server">
</asp:ContentPlaceHolder>
</div>
<div id="rodape">
<uc3:Rodape ID="Rodape1" runat="server" />
</div>
</form>
</body>
</html>