We are aware that some Epic Games Store users were encountering an issue with their existing game purchase or upgrading to the Year One Edition. As of now, that issue should be resolved.
Owners of the base game are able to upgrade to Year One Edition to access our first two DLC packs alongside the Living Weapons content pack, on sale for a limited time.
Deluxe (AKA Platinum for our backers) game owners are also eligible to upgrade.
Season Pass owners have the same content (DLC 1-2) which is present within Year One Edition. Upgrading your edition of the game will allow you access to the Living Weapons pack if you do not own it already.
Ultra edition owners (or Signature for backers) are not currently upgrade eligible as those owners already technically have all the content being offered. Again, please note that the only difference for those owners is the Year One Edition home screen in-game. All content otherwise is the same.
If you are still having a problem upgrading or accessing owned content, please reach out to Epic Games Store technical support via https://www.epicgames.com/help/