FAQ #15680, published on 2017-10-19
How to deal with the "HTTP Error 503. The service is unavailable" on Windows 10 after installing the Fall Creators Update ?
This HTTP Error 503 occurs just after the installation of the Fall Creators Update for Windows 10. The problem is directly caused by the Fall Creators Update. Microsoft is aware of that and the solution can be found here :

https://support.microsoft.com/en-us/help/4050891/error-http-503-and-was-event-5189-from-web-applications-on-windows-10



See also : HTTP, 503, Fall, Creators, Update, Windows, IIS