The iPhone could not be updated. an unknown error occurred (14)

You do have a point Lawerence about the back up options, but in my opinion, regardless of having the option of backing up your data, it is NOT ACCEPTABLE in this situation that the operating system can't give you a warning that your device (iPhone) is running low in space and that it won't be able to re-start. I shouldn't have to check the phone every day to see if I still have enough space, and how much space IOS need to safely boot.

It happened to me yesterday and I am very angry and frustrated at this. I got an app crashing a few times, so I decided to reboot my phone as I normally do when I notice an app behaving weird, or every few days. And this time, it couldn't boot. It got stuck in the apple logo. Tried doing a hard re-start several times, but the same thing. Then the only option left to try was to update the phone through iTunes as recommended by Apple, and I am assuming, that because there was not enough space... the update failed half way through, and boom! error 14. I've tried all the suggestions (different USB cable, port, etc) without any luck. Now the only option I have is to restore my phone. I do have a more or less recent back up, but still, not everything is in it and I do have some data in that phone that I don't want to lose it by having to do a restore.

Come on Apple, help us out and come up with a fix for this!!

It probably was not on the latest software; there are sometimes releases that don’t change the version number (called “slipstream” releases) that are simple patches. And sometimes a version gets corrupted and needs to be reinstalled.

Drive savers cannot recover data from a disabled phone. No one can.