Fortunately, there is an third-party tool Syncios Mobile Phone Manager that makes iphone backup and restore much easier, which lets you transfer music, videos, photos, contacts, messages, apps, etc between i Phone/i Pad/i Pod and computer within one click.With Syncios, you can backup & restore everything on your i Phone easily whenever you need, manage i Tunes library, playlist, make ringtone, download Youtube video to i OS devices freely.
As per the reasons showing above, various reasons may result in the i Tunes error 29.
The error itself was not that annoying, but the Apple's none effective fix which upsets the users.
If the Settings app doesn’t work, try using i Tunes. I highly recommend backing up your i Phone to i Tunes or i Cloud before starting the update process.
When Apple releases a new i OS update, millions of people are connecting their i Phones to Apple servers to download and install it.
With all those people connecting simultaneously, Apple’s server may struggle to keep up, which could be the reason why your i Phone won’t update.