IIS7 custom 404 not showing

Question

created a new IIS7 web site with Intergrated .net 4.0 app pool.

URLs ending with .aspx do show custom 404 anything else gives the blue server error page \"HTTP Error

Answer 1

I was having this issue with my web app and I got it resolved by commenting out the redirect line:

On IIS, the allowAbsolutePathsWhenDelegated (on Configuration Editor --> system.webServer/httpErrors) was locked and I can't change the value false to true.