The Controls collection cannot be modified because the control contains code blocks (i.e. <% %>)

This one hit me some time ago but was easy to work around. Today I had to face it in a ListView's LayoutTemplate:

<LayoutTemplate>

    <asp:PlaceHolder runat="server" ID="itemPlaceholder"></asp:PlaceHolder>

    <% if ( ApplicationUser.IsCurrentUserTheAdmin )

       { %>

    <hr />

    <asp:ImageButton ID="SwitchAddSectionButton" runat="server" OnClick="SwitchAddSectionButton_Click"

        ImageUrl="~/Resources/item_add.gif" />

    <% } %>

</LayoutTemplate>

As you can see there is a dynamic part of the template which is available to users with sufficient priviledges.

Although google provides a lot of articles referening the issue, the solution I've came up is amazingly simple:

<LayoutTemplate>

    <asp:PlaceHolder runat="server" ID="itemPlaceholder"></asp:PlaceHolder>

    <div runat="server">

        <% if ( ApplicationUser.IsCurrentUserTheAdmin )

           { %>

        <hr />

        <asp:ImageButton ID="SwitchAddSectionButton" runat="server" 

            OnClick="SwitchAddSectionButton_Click"

            ImageUrl="~/Resources/item_add.gif" />

        <% } %>

    </div>

</LayoutTemplate>

Note that the only difference is the <div ... runat="server"> tag which contains all other additional controls in a control tree.