Debugging ASP Applications
Although the primary focus of web debugging in Visual Studio 2012 is ASP.NET, you can also debug legacy ASP web applications.
ASP web applications consist of scripts, which run on the client in .htm files and on the server in .asp files; the Global.asa file; and .cdf files. Scripts can be in VBScript, JScript, or a mix of VBScript and JScript. They may also be mixed with HTML code and COM objects. You can debug ASP web applications containing all of these elements.
In Visual Studio, you can debug client-side script running on your local machine by attaching to a local copy of Internet Explorer. To debug script running on Microsoft Internet Information Services, you can attach to IIS on your local machine.
ASP code can execute in the Inetinfo.exe process (in-process execution) or in a separate Mtx.exe process (out-of-process execution). To debug ASP code, you must attach to the Inetinfo.exe or Mtx.exe process. To debug client-side script as well, you must also attach to IExplore.exe. For information on how to attach to processes, see Attaching to Running Processes.
When you attach to an ASP web application, make sure you select the appropriate program types in the Attach To Process dialog box. When you debug script, Managed code must not be selected. You cannot debug script and managed code at the same time in Visual Studio 2005.