Support

The URL parameter does work. I am saying this having used it more than ten times just today and just on this site. Please note that the URL parameters should best only contain lowercase letters a-z and numbers 0-9. Other characters may not work on some servers, depending on the way URLs are encoded by the server software before being made available to PHP. Question marks, ampersands and equal signs have special meaning in URLs and will definitely not work in the secret URL parameter.

As to why the custom admin directory was removed, it has to do with the way a lot of shared servers handled it. If we fixed this feature on those servers it stopped working on the majority of properly configured servers. If we made the feature to work on the majority of properly configured servers it didn't work on the affected shared servers. This has resulted in a constant stream of support requests which are unresolvable and a major point of friction between us and our clients. The only decent thing we could do was remove the feature which cannot be made to work with the vast majority of servers. We have a rule: if it cannot be made to work on over 95% of the servers used by our clients we don't include it. Besides, it didn't offer actual security. Using the administrator password protection and Joomla! 3's two factor authentication (a feature we contributed to the Joomla! project after having it for over two years built in Admin Tools Professional) is a far better solution.

If your IP address is in the Whitelist (and you have activated the IP Whitelist feature) or in the "Neve block these IP addresses" then no security check is performed for any requests coming from these IP addresses. This means that you are exempt from the secret URL parameter too. Try accessing /administrator from a different computer, tablet or mobile phone connected to a different Internet connection, e.g. a tablet over 3G/4G. You'll see what I mean.