In this tip, you will learn what happens when you place an App_Offline.htm file in the root of a web application directory, and also what happens when you remove the file.
If you place a file with the name App_Offline.htm in the root of a web application directory, ASP.NET 2.0 will shut-down the application, unload the application domain from the server, and stop processing any new incoming requests for that application.
ASP.NET will also then respond to all requests for dynamic pages in the application by sending back the content of the App_offline.htm file (for example: you might want to have a “site under construction” or “down for maintenance” message).
Once you remove the App_offline.htm file, the next request into the application will cause ASP.NET to load the application and app-domain again, and it will be back to normal.
