Master Page Weirdness - “Content controls have to be top-level controls in a content page or a nested master page that references a master page.”

Question

This is weird. I added a brand new Web Application project to my solution in Visual Studio 2008.

Created a master page. Made zero modifications. Created a new we

Answer 1

I just encountered this exception and in my case it was cause by a white space between asp:content elements

So, this failed:

<asp:content runat="server" ContentPlaceHolderID="Header">
    Header
</asp:content>

<asp:Content runat="server" ContentPlaceHolderID="Content">
    Content
</asp:Content>

But removing the white spaces between the elements worked:

<asp:content runat="server" ContentPlaceHolderID="Header">
    Header
</asp:content><asp:Content runat="server" ContentPlaceHolderID="Content">
    Content
</asp:Content>