This might be a little ironic @the_rock , but it's possible that the errors you got were not related to installing JHF or rebooting the Management.
The original post in this thread by @FuzzyLogic was to make people aware that they need to select the Management object, otherwise they will get an error "Failed to collect (get) domains". That's the error that you got, so it's highly possible that you simply selected a gateway object when you ran the script, instead of the management.
Thanks @Omer_Kleinstern for pointing out that possibility.