Several users have reported an issue in which the iPhone and iPod touch become indefinitely stuck on the backup phase of the iOS 4.0 Update. Other users report that the backup process is inordinately slow after the update, taking up to 3 hours in some cases.
Fixes
Disable network connection. In some cases, simply disabling your network connection (turning off AirPort or unplugging your Ethernet cable) will resolve the slow or stuck backup phase. It appears that iTunes performs some data network data transfer during the backup process which can, for unknown reasons, take an extremely long time or become stalled.
Restore instead of update. Backup your iPhone or iPod touch, then perform a restore process instead of using the check for update function. This may allow the iPhone or iPod touch to successfully receive the iOS 4.0 update, after which sync processes should occur at normal speed.
Switch USB ports. Try switching your iPhone or iPod touch to a different USB port. In particular, if you are using a hub or other intermediary device, try connecting the device directly to your computer.
Feedback? info@appletoolbox.com.
March 5, 2011 at 1:40 PM
using the restore method is effective and fast to update software and solve the the problem. I just syn, then restore and update, and tick all my apps in itunes and syn them back to my iphone! The whole process took around 2 hours, but definitely better than being stuck in the back up phrase! Thanks !!
April 5, 2011 at 12:37 AM
To back up iPhone data before updating I used the method in the link/URL below; by accessing the root directory and copying the Library>Documents Folder
http://surreystore.com/cms/articles/7-apple/32-how-to-back-up-data-before-update.html
Worked like a charm!
April 7, 2011 at 1:17 PM
umm yea thanks for telling me to sync it to my computer first…… backed it up and restored it and pretty much lost everything….. explain ur shit people!
December 29, 2011 at 10:23 PM
I must say I did the same thing as Guy (above). Perhaps we need to modify your article so we all don’t lose 6 months of data!
January 4, 2012 at 1:12 AM
Did you try this? Found this in several places and it works for me
1. Quit iTunes.
2. Start an elevated command prompt (Start Menu -> All Programs -> Accessories -> Right Click “Command Prompt” -> “Run as Administrator”)
3. Once in the command prompt, type “netsh winsock reset” and hit ENTER.
4. Reboot your machine.
5. Restart iTunes.
January 15, 2012 at 5:10 AM
Many thanks to all –
Finally got 4.2 installed using ‘restore’ where it had previously hung at the ‘backing up’ stage……
Disconnecting internet and winsock reset had both been tried, with no improvement.
Nearly got tempted to abort the ‘restore’ as it was apparently stuck at the ‘calculating time……’ stage, but left it alone and it finally came good after an hour or so.
May 7, 2012 at 12:58 PM
This works.
May 7, 2012 at 12:59 PM
I mean the windsock reset works