Change http status 404 to 503 when serving app_offline.htm

Question

We added app_offline.htm. All request return something "Site under reconstruction" and 404 error. What I may do for return 503 error?

Answer 1

We use asp.net 2.0. I created new pool ASP.NET 4.0 and attached web-site to it. And then http status returned is 503.

To clarify, when using app_offline.htm ASP.NET 2 returns 404 and ASP.NET 4 returns 503 status code.