Re: I purchased the Hardened Edition for Xbox 360. Now I have the Xbox One, when I try to use the "Add On" to update it says "Unavailabe". Do I have to buy another Hardened Edition set for Xbox one now?

Nemesis,

It is not the Hardened Edition you need to download on the Xbox One.

You bought the 360 Hardened Edition which gave you the Season Pass,, and it is able to be transferred for free to the Xbox One.

You need to go to the Add-On section and click on Season Pass - it should say already purchased, download.

Then you can download the Onslaught map pack.