why is there an error in updating IOS 7.1

Are you getting a specific error message? Are you updating through iTunes or WiFi?

Any error number or text of the error?

Are you trying to update via wifi, or connected to your computer.

iPad: Unable to update or restore

http://support.apple.com/kb/ht4097

iTunes: Specific update-and-restore error messages and advanced troubleshooting

http://support.apple.com/kb/TS3694

If you can’t update or restore your iOS device

http://support.apple.com/kb/ht1808

 Cheers, Tom 😉