Content controls have to be top-level controls in a content page or a nested master page that references a master page
asp.net, c#, master-pages, web-content
Solution
The HTML-code in your nested masterpage must be wrapped with an asp:content-tag with a contentplaceholderid from the "master" masterpage.
Problem
I want to use nested master page so i create the following master page : ``` <%@ Master Language="C#" AutoEventWireup="true" CodeBehind="test.master.cs" Inherits="DocumentFlowUI.test" MasterPageFile="~/MasterPage2.master" %> <!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></title> <asp:ContentPlaceHolder ID="head" runat="server"> </asp:ContentPlaceHolder> </head> <body> <form id="form1" runat="server"> <div> <asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server"> <asp:Button ID="Button1" runat="server" Text="Button" /> </asp:ContentPlaceHolder> </div> </form> </body> </html> ``` and i create the following page to use that master page : ``` <%@ Page Title="" Language="C#" MasterPageFile="~/test.Master" AutoEventWireup="true" CodeBehind="WebForm4.aspx.cs" Inherits="DocumentFlowUI.WebForm4" %> <asp:Content ID="Content1" ContentPlaceHolderID="head" runat="server"> </asp:Content> <asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" runat="server"> <asp:Label ID="Label1" runat="server" Text="Label"></asp:Label> </asp:Content> ``` I get the following error : Content controls have to be top-level controls in a content page or a nested master page that references a master page