This may be due to a hardware error, or maybe there is a communication failure between your device and the servers.However, fret not, we will show you how to fix that i Phone Error 21 easily and effec-tively and get back to leading your i Phone engrossed lives!
2) Select both i Tunes and Bonjour, click Uninstall. 1) Make sure that you have quit i Tunes if it opens. If Apple Mobile Device USB Driver option cannot be found under category Universal Serial Bus controllers, but under Portable Devices, please go to Method Five: Update i Phone 7 Driver. Then navigate to C:\Program Files\Common Files\Apple\Mobile Device Support\Drivers. If you have a 64-bit version of Windows, this file will be called usbaapl64. If it prompted to say that the software that you are installing has not passed Windows Logo testing, click Continue.
Driver Easy will automatically recognize your system and find the correct drivers for it.
You don’t need to know exactly what system your computer is running, you don’t need to risk downloading and installing the wrong driver, and you don’t need to worry about making a mistake when installing.
3) Press Windows key and R at them same time, then type in and hit Enter. When you see this, it is suggested that you update your device driver right away.
4) Locate Apple Mobile Device or Apple Mobile Device Service, then double click it. If you don’t have the time, patience or computer skills to update your drivers manually, you can do it automatically with Driver Easy.