Default.aspx in a virtual directory raises a CS1061 error

Question

I'm staging an ASP Web Forms application for system testing. We have two URLs that will use the same code, changing their content based on the URL. So I configured two virtual directories in IIS to map to one physical path. Say the virtual directories are TTP/Site1 and TTP/Site2, and they both map to TTP/SiteCommon.

However, the Default.aspx page raises a CS1061 compilation error:

CS1061: 'ASP.ttp_site1_default_aspx' does not contain a definition for 'btn_login_Click' and no extension method 'btn_login_Click' accepting a first argument of type 'ASP.ttp_site1_default_aspx' could be found (are you missing a using directive or an assembly reference?)

The error is on this line:

<asp:Button ID="btn_login" runat="server" Text="Log in" OnClick="btn_login_Click" />

I get the same message for TTP/Site2, and on the same line.

I looked up prior Stack Overflow questions, and confirmed that btn_login_Click in Default is protected not private.

Any ideas?

ETA per request:

    protected void btn_login_Click(object sender, EventArgs e)
    {
        Response.Redirect("~/login.aspx");

    }

ETA2:

<%@ Page Title="" Language="C#" MasterPageFile="~/main.Master" AutoEventWireup="true" CodeBehind="Default.aspx.cs" Inherits="RIF.Default1" %>

Answer 1

Make sure your class is named Default1 and it's in the RIF namespace.

Also, if you're using Web Site instead of Web Application Project, change CodeBehind to CodeFile. See MSDN.

<%@ Page Title="" Language="C#" MasterPageFile="~/main.Master" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="RIF.Default1" %>