My iPhone still stuck on Syncing and Backing up

Try to delete the latest backup in iTunes/Edit/Preferences/Devices, if iTunes can't read the last backup you made, in order to replace it with the new one, the sync process will stop.

If you have a large number of photos on your phone, copy them to your computer and delete them from the camera roll, damaged photos can also cause the process to hold.

iOS: Improve backup and restore times by importing Camera Roll or Saved Photos

Can you back up manually by right clicking on your phone in the device list and choosing "backup"?

To make sure the problem is not on your iTunes side, create a new user on your computer, log in, set up your iTunes account, make sure autosync in iTunes is not active and try to back up manually. Be aware, that syncing to an empty address book will erase your contacts on the device as well. Set up one event and contact on that account before syncing.

Did you already try to reset the phone by holding the sleep and home button for about 10sec, until the Apple logo comes back again? You will not lose data doing a reset, but it can cure some glitches.

If this does not help, back up as much data as you can by copying the photos to your computer, described in this article, and set it up as new device after that. There seems to be no other way than to restore.

How to back up your data and set up as a new device

Apps can be downloaded again for free, if you don't have a backup, you'll "only" lose app related data or settings.

Downloading past purchases from the App Store, iBookstore, and iTunes Store

deleting last backups did nothing here

still stuck at 99% on step 2 of 6 using latest itunes, imac, iphone4s 6.1.1

imac is very hot as its been trying to sync for 3 days lol

already restored iphone 10+ times and reinstalled itunes due to all my icons flashing and saying waiting... everytime i reboot, this is just so much fun!!!!!!!

im gonna need apple to pay me for the time ive wastedover the past 3 days, ill take a grand and my pick of hottie from my local apple store 😉

@leetut

did you already try this on a different computer?

i tryed this and it worked. it didnt back up my phone but i never wanted it backed up in the first place. http://www.youtube.com/watch?v=CpOm6ylArqU

I had this issue and found the solution.

Problem:

I would set my phone to sync with iTunes. iTunes would cease all syncing animation leading me to believe the sync was complete, but on my iPhone the spinning animation would continue. I would open the sync menu in settings and the cancel sync button was still available, leading me to believe the phone was still syncing.

I canceled the sync on my phone to no avail. Phone would still try to sync. I would restart my phone and songs would be missing. I restored my phone as new and got the same issue.

Solution:

After iTunes says the sync is complete, and the phone continues to sync. Leave the lightning cord connected and iTunes open because the phone IS STILL SYNCING. Open iTunes on your phone and click songs, not artist or album. Scroll all the way to the bottom where it shows how many songs are on your phone. You will see the numbers are still climbing as songs are still downloading to your phone. These climbing numbers will gauge how much time you have left to wait.