Hey all!
FIrst, I think it's clear there is more than one cause of this error, so sorry if this does not work for you, but here is a suggestion which I don't think has appeared in this thread and worked for me! If you have tried everything else, give this a go:
- Go to Settings>iCloud>Family
- Click on the name of the user of the iPad/iPhone with trouble (the user with"(me)" at the end)
- Make sure that the account name under "family purchases" is the same as the AppleID for that family member. If it is not click on the account name, in blue, and log on with the family member's AppleID in the dialog box that opens.
Although that was the problem to fully get things working I then had to
- log out of the App Store and log back in again (so it realised I had made the changes above)
- download any old free app, so it correctly populated "My Purchases"
I think maybe these would have fixed themselves, in time, but the two steps above forced a refresh and got things working immediately.
Somehow the iPad I had with trouble with was logged on to iCloud with the right AppleID, but that AppleID was set to share purchases from a different AppleID (in fact mine), probably because iCloud was previously logged in with that AppleID before Family Sharing was released. I have no idea why Family Sharing gives you the option to share apps from a different account to the user logged into iCloud. All it seems to do is break the App Store completely.
I was left with 2 apps that would not update, but that was because they were not enabled for family sharing. Luckily, they were both free apps and I was able to uninstall and reinstall to get them working.
One last thing: When "updating all" the App Store seems to work its way down the list. If any one fails, it stops. So if you have tried ANY of the ideas in this thread it is worth checking that the top app in your update list is not disabled from family sharing (shown under "information" on the apps page in the App Store) or it may prevent all the other apps from automatically updating. If it is try uninstalling and reinstalling or manually updating one of the other apps in the list.
