XBox Series X - Error 315306

[SupportalKom-1714]

I bought the Ultimate Edition on this console, and can log in every time, no issue.
My couch co-op buddy tries to log in on the same console and we always get Code 315306.

Update:

No joke game share fix!

After struggling to get this to work all day I can finally validate a work around to anyone experiencing game share problems! Requirements: 2 controllers Step one! Make sure both the account that purchased the game, and the account you’re trying to share with are on the same console Step two! Start diablo 4 on account that purchased the pre order Step 3! If a character has already been made, must create a new character on account that has purchased the game, at this point before starting …

Use this method. It worked for us. After they finish the prologue (make sure they finish it), everyone needs to logout. The license holder needs to log in, select character they wish to play, and choose the world tier they were not on (only temporary), and then enter the game.
P2 can then join on their character and your quests should show as “Shared” (not “Limited”)

[Nibbles-11438]

Same here. If I log in and get in game, my partner can log in and create an account but they can’t play bc their newly created character isn’t allowed to join.

[RGO-1726]

This is happening to me too, frustrating paying for early access to not be able to use it.