"Same problem. My iPhone 6s won't sync to iTunes after iOS 10 update"
More and more iOS users complained that iTunes can't sync with iPhone. This sync error also happens to iPad and iPod. Some users can't sync songs/videos from iTunes library to iPhone, some have the iTunes is stuck 'preparing to copy items' error when sync iPhone, some find that iPhone/iPad won't sync to iTunes after restore or after iOS 10.3/10.2/10/9.3/9 update, and even some discover that iOS device won't sync to iTunes after iTunes updating to the new version (such as iTunes 12.6, 12.5, 12.4, 12.3, 12.2, 12.1, 11.3/11.2).
You can try each in descending order until the problem is resolved. All of them works for all versions of iTunes and iOS devices including
Note 1: Those tips are aimed at resolving actual problems (i.e. the syncing or data transfer between iTunes and iOS device), not at problems with detecting the devices themselves. If iTunes can't recognize your device, go to the article Free Fix iPhone, iPad, iPod Is Not Recognized in iTunes.
Note 2: if you only want restore your iOS Devices, You can go to Restore iPhone from iCloud Backup, or you have no iCloud Backup, you can go iTunes backup extract software that can restore you iTunes Backup data to PC/Mac.
Sometimes just updating iTunes to the newest version is enough to resolve the syncing problem. On iTunes, Windows users go to Help menu and select "Check for Updates"; Mac users go to iTunes > Check for Updates. If there is a new version, update your iTunes.
You can quit out of iTunes and then restart the app. Then you should try manually syncing again. If syncing works normally but no music, movies or apps copied over to your iOS device, you can try the methods to fix this syncing issue in the article iTunes Music Not Syncing to iOS Device.
Sometimes iTunes failed to sync iPhone or iPad may due to corrupted files, try Free TunesCare to fix iTunes sync problems quickly.
If the Sync button is grey and not available at all, or when you try to sync nothing transfers over to the iPhone, iPad, iPod, you can try deauthorize and authorize your computer.
To do this, connect your device to computer and open iTunes > go to Store and select "Deauthorize this Computer" > input your Apple login > after that, click on Store again and click "Authorize this Computer" > enter your Apple login details again.
If iPhone/iPad/iPod won't sync to iTunes over Wi-Fi, try a USB cable instead. If you have already used a USB cable to sync, turn to Wi-Fi. Since we have dedicated how to use iTunes to sync or transfer data to iOS device via USB or Wi-Fi in the article Transfer Files from iTunes to iPhone, you can check to see the details.
In some cases, your iOS device may fail to connect to Wi-Fi. Go to the tips in iPhone Won't Connect to Wi-Fi to fix wireless connecting problems.
Sometimes this syncing problem is caused by wrong USB port or connection. Make sure your iDevice isn't plugged into an unpowered USB hub. Try another USB cable or try to plug into another port of your PC or Mac.
Some other phone and cellular device connectivity software may cause this syncing issue. You can uninstall the phone or cellular connectivity software temporarily.
Original factory settings restore will help to fix this "iTunes won't sync with iPhone/iPad/iPod" issue.
To do this, connect device to computer and run iTunes > go to "Summary" and select "Restore" > confirm the restore in the pop-up window. When finished, set up your device as new.
iOS devices like iPhone or iPad require Apple Mobile Device Support and it should be automatically installed with iTunes. If you miss this support, iTunes may not detect your iOhonw can you can't sync iOS device with iTunes. You can check on Windows OS like this:
If you find Apple Mobile Device Support is not installed, then reinstall iTunes.
Share this text with anyone you know so that you can help out when they meet the same problem. iTunes will sync data such as music, videos, contacts, photos, notes with iPhone, iPad, iPod normally after you try the tips above.