@phillxnet thanks for tagging me into this response and the other thread. I have followed this link that you added to the thread
Distribution update from 15.3 to 15.4 — Rockstor documentation
Of course made the necessary changes to the version number and I was able to upgrade to 15.5 version.
The one observation that I would make is that the Rock-Ons did not all work. A simple Stop/Uninstall/Install resolved all my installed Rock-Ons and the platform is working well.
Thanks
Andrew