To all the people saying that the backup eventually worked, have normal backups continued on a routine basis?
On iOS 8.4.1 and earlier, my iPhone used to backup to iCloud on a nightly basis every time I plugged it in at the end of the day.
On iOS 9, since the upgrade, I have had 1 seemingly successful backup. But, there are still two problems:
(1) I have no faith that the backup worked properly, because the amount of data listed for each app appears to be way off. I only have 4 photos in my camera roll, but it says camera roll is taking up 120MB, which is not possible. I also have hundreds of MBs of data in GoodReader, but it shows GoodReader only takes up 23MB of space in iCloud (again, not possible).
(2) Although I have had that one backup, it has not backed up since that one time.
Additionally, to all of those people claiming it's a server issue, that definitely does not appear to be the case. That is, I don't think it's JUST a server issue. I say that because after upgrading my two devices to iOS 9 and having this problem, I decided against upgrading my wife's devices. So, my devices (which are on iOS 9) don't backup, while my wife's devices (on iOS 8.4.1) backup without problem every single night. If this was purely a server issue, it would seem that the devices wouldn't be split between iOS 8 and 9 like they are in my house.
I just got off the phone with Apple support, and the representative that I spoke with had no idea how to fix this, and was not even aware that so many users are experiencing this problem. This doesn't sound to me like a fix is imminent.