[Diablo 2 Resurrected] CD key is being used by SELF problem July 27, 2021 | Battle.net US East Realm
To install Diablo II you must enter a Diablo II key. You cannot use a 16 digits physical CD key to install online. Please redeem your 16 digit physical CD key on your Battle.net account. This will convert it to a new 26 digit digital license key that will be permanently stored on your Games & Subscriptions page.