Maintenance Page Take App Offline! Magic with App_Offline.htm

Overview

The App_offline thing is around for quiet long time and I haven't seen enterprise level system use it. Either they do it using at load balancer end or redirect to some third party hamster page until the site is provision for up and running. Leaving the real time usage and know-how.

Headstart

Refer this: http://geekswithblogs.net/Vipin/archive/2012/03/28/app_offline.htm-taking-site-down-for-maintenance.aspx

Here are quick help tip if you want to enable it.

Key Note

Remember just putting App_offline.htm in the root folder of the website will just stop the further processing of request and always return =

Http Status 503:

The service is unavailable.

If you really want to show up App_Offline.htm custom page you must add this in your web.config file

Refer this for more information
https://stackoverflow.com/questions/17135109/app-offline-site-returning-the-service-is-unavailable

One can even try to automate this using FTP command and powershell or either use out of the box option in VSO Build and Release pipeline.

https://stackoverflow.com/questions/20792405/how-to-take-web-app-offline-while-publishing

Take App Offline option under Deployment