Here check full guide to make a smooth upgrade to i OS 10 With i OS 8 has just arrived, you may feel excited to update your Apple devices to i OS 8.
Upgrading to i OS 8 is pretty simple, you just need to click Update on i Tunes or Install Now on an i OS device.
In fact, it is far from enough, you need to transfer photos, videos, music and other files from computer to device; recover lost info if necessary; extend the battery standby time, etc.
Read More about What to Do After i OS 8 Update i Mobie aims to offer the best i OS data transfer, recovery and cleaning tools to help you figure out practical problems.
Connect your i Pad to your computer and open i Tunes. If there is less than 5 GB free space, delete movies, music or larger apps until there is space (you can reinstall easily after the update). i Tunes will download the proper update from Apple and do everything necessary.
If it still complains, do this: While connected to i Tunes, click "Backup".
I updated with i Tunes on my PC but it says that it cannot update my i Pad! You mentioned though that you "bought" the i OS 8.1.1 IPSW. If you paid for it, you should immediately demand your money back.