Q: I am trying to upgrade my iphone 5 from iOS 6.14 to iOS 9.2.1 and I m getting the below error:unable to install update an error occurred installing ios 9.2.1, Please help!!

Since you're changing major versions (6 to 9), the full installer needs to be downloaded. Then it has to be verified and unpacked. Then there needs to be room to write out the new while the old is still partly around. This spells out requiring at least 6-7GB of free room on the device for an Over The Air update to even have an inkling of a chance to succeed.

If you do it using the iTunes program on a computer (Mac preferred), the downloading, checking and unpacking occurs in the computer (which usually has vastly more resources than the phone), reducing free space requirements to about 1-2 GB.

To add to Courcoul's excellent comments, since you waited about three years to upgrade iOS, it seems very likely your computer does not have current software either.

As Courcoul states, you should probably rely on iTunes on your computer to perform your upgrade.  However, if you do this, you will need a relatively current version of iTunes to succeed.  (The current iTunes version is 12.3.2.)  However, to use this version of iTunes, you will also need a relatively current version of your computer's operating system.

In the future, I strongly suggest you perform more frequent updates/upgrades which would therefore be more incremental than less frequent huge upgrades.

iTunes 12.3.2 needs OS X 10.9 Mavericks as a minimum on a Mac.

Or do it on a PC with Windows 8 or newer.

Courcoul wrote:

 

iTunes 12.3.2 needs OS X 10.9 Mavericks as a minimum on a Mac.

Actually, it could work with Mountain Lion OS X 10.8.5.

Courcoul wrote:

 

Or do it on a PC with Windows 8 or newer.

Actually, it could work with Windows 7.

You will agree that the MBP has vastly greater resources than the phone. Networking ensures the installer gets downloaded faster and with less risk of failure, storage ensures there will be plenty of room to store and process it, CPU offers speedier processing (validate, unpack and carry out the necessary upgrade procedure). All this translates to a more reliable, safer and dependable upgrade process that reduces stress on the phone in terms of time, processing and mandatory free space. And, to boot, you get to have an up to date backup of the phone's contents.

How would I do this via itunes?  I am also getting the same error.  I want to get a new phone but before I can I need to get all the pics off my phone.  I cannot download to icloud with this old version.  Its a catch 22