Q: Mac OS X 10.11.6 The server gave an error during download: 503 Service Unavailable. when downloading updates in the Mac App Store

The Mac App Store server may be down temporarily. Try again later.

Hello Carolyn. I am the in-house family Apple tech support for my husband's account. The Mac App Store server was not down. It took me 4 hours of my time today to unravel what the problem was and to fix it. Of their own accord, our bank changed its credit and debit cards from MasterCard to Visa recently when it issued new cards with chip technology, and one of those cards was the default card for payment in the Mac App Store and for Apple Pay on our iOS devices Apparently without a valid credit card on file, the Apple server will not download updates properly or at all. Which is an odd requirement for free updates, but that was the problem. Once the new information was entered the updates magically happened immediately. The completely inane error messages were absolutely no help at all. And to complicate matters the problem appeared on a family sharing account's Mac (my husband's), not the family Organizer's Mac (mine), and the information had to be updated on the family Organizer's account (mine) before the default payment would change on the family shared account's Mac and iOS devices. And even with the new information entered via my organizer account on my Mac, it would not update on the family shared account's Mac until the information was entered in Apple Wallet on my iOS device. What a mess and tangled web. And the meaningless error messages were completely misleading and unhelpful. The only way I was able to figure it out is that one error message finally popped up in iTunes  (not the Mac App Store) after 3 hours of my trying everything I could think of to get the updates to download on the family shared account's Mac to no avail) that said something to the effect of "there is something wrong in your iCloud account".

I guess I am not the only one. I cannot download even macOS Sierra beta and free updates for other apps. BTW the Mac App Store server is still not down. I even reinstalled my Mac. Something wrong with it?

10.11.6

As I posted above, check your payment information in the Mac App Store, iTunes, iCloud, and Apple Wallet (all of them) and make sure that you have a valid credit card on file that has not expired. If any one of them is not up-to-date, the updates do not update properly or at all.

This solved my problem.  Thank you!