In transaction SICF:
1. An external alias is maintained for a service node.
2. For this external alias, under "Error Pages" section, a custom page (Explicit Response Page Header & Body) is maintained for 'Not accessible' tab.
3. The service node itself is made inactive/deactivated.
4. For a request sent to such an external alias, the custom error page maintained for 'Not accessible' tab is not shown/returned and instead, the standard default 403 - Forbidden error page is shown.
The custom 'Not accessible' error page maintained for an external alias that points to a deactivated service, is not returned due to a program error. This happens only for SAP_BASIS 700. All the higher SAP_BASIS releases work as expected and show the custom error page