Cannot enter the game because I was 30 days offline

Hey there Palaham,

I looked into this as there are a few reasons it can occur. Checking the account, I found a refund for Diablo 2: Resurrected was done a few months ago. Since the account does not have the game any longer, that error will occur. You’ll want to repurchase the game in order to play Diablo 2: Resurrected again.

You can also check your order history here.