Can't restore from iCloud backup in iOS 10
If the backup is corrupt, you'll be out of luck.
If it's just that Apple's servers are swamped right now, after the iOS 10 launch, then you may have better luck tomorrow or the day after.

It seems time to trot out the old adage...

"Any data not stored in at least three distinct locations ought to be considered temporary."

Even though you got away with it 9 times out of 10, there's always a 10th time.
Somebody gets bricked with every update; make sure it's never going to be you.
Backups are those useless things that take up valuable storage space &amp; are totally pointless...
...until the day you need them.

You really should also have had a local iTunes backup, encrypted to preserve passwords etc, &amp; that backed up to Time machine.
Optional off-site copy too - Backblaze etc -  in case the building burns down.

The smartest way to do any update.


Launch iTunes, plug in device.
When asked if you want to update click Download Only.
Whilst that's busy, switch to the Apps view in iTunes - download all available updates.
When complete, switch to your device view &amp; Sync.
Back Up Now [with encryption, which preserves your passwords]


You now have fully up to date retrievable restore point, should anything go wrong.


Once the iOS download is completed, then you can Update.