ASP.Net URL Routing: Still page contains .ASPX extension

How you are redirecting to the Page

<a href='<%=ResolveUrl("~/Customers") %>'>View Customers</a>

If you write like above then it will show the url like this.

http://localhost:1932/RoutingCS/Customers

You need to set the Startup page as

Add this rout in the Sample

routes.MapPageRoute("Default", "Default", "~/Default.aspx");

Complete Global.aspx

<script runat="server">
    void Application_Start(object sender, EventArgs e) 
    {
        RegisterRoutes(RouteTable.Routes);
    }
    
    static void RegisterRoutes(RouteCollection routes)
    {
        routes.MapPageRoute("Default", "Default", "~/Default.aspx");
        routes.MapPageRoute("Customers", "Customers", "~/Customers.aspx");
        routes.MapPageRoute("CustomerDetails", "Customers/{CustomerId}", "~/CustomerDetails.aspx");
    }
</script>

Download the sample and check

You need to understand that if Routing does not mean it will automatically convert http://localhost:49702/DailyLog.aspx to http://localhost:49702/DailyLog/

You yourself have to type http://localhost:49702/DailyLog/

in the browser and see if it works or not and also change all links in your site to use http://localhost:49702/DailyLog/ instead of http://localhost:49702/DailyLog.aspx 

First of all if its inside some folder that has to be included in Routing

routes.MapPageRoute("404", "ErrorPages/404", "~/ErrorPages/404.aspx");

Also you are still not understood anything from my last reply that if you want to use Routing you need to update all links

<error statusCode="404" redirect="ErrorPages/404.aspx" />

must be

<error statusCode="404" redirect="ErrorPages/404" />