Problem to initiate update for iOS 8 I have a iPhone 5s, and have still not received any information about on-the-air update to iOS 8. So I decide to update manually through iTunes. iTunes gives me an assuring message


  iTunes will update your iPhone to iOS 8.0 and will verify the update with Apple.


and when I click OK, nothing happens. No user interface change, no network usage by iTunes, no error messages, nothing at all. And if I click Update button again, the above message shows up again.

Do anyone have a clue how to fix this?
Go into your iPhone's Settings. Select General -> Software Update. Here you can initiate an OTA update. (right now you will be placed in a waiting queue which could range from a few minute to a few hours due to demand).