What does it mean when I try to redeem an Apple gift card and get pop-up that says: Error Code redemption is currently not available. If I check balance on the gift card, I see the amount I expect.

What does it means when I try to redeem an Apple gift card and get pop-up that says:

Error

Code redemption is currently not available.

If I check balance on the gift card, I see the amount I expect.

Does redemption have to happen within certain business hours? Can redemption be blocked by firewalls or script blockers? Does this only happen rarely and I just happened to be unlucky the first five times I tried it?

Thanks!