iOS 4: Updating your device to iOS 5 or later
Summary
To update your iPhone, iPad, or iPod touch from iOS 4 to iOS 5 or later, you must erase and restore your device first, before completing the update.
Products Affected
iPad, iPhone, iPod touch
As part of the update and restore process, iTunes will (in order):
- Back up key elements of your device, such as settings, Contacts, Calendars, Notes, and your Camera Roll1. iTunes will not, however, back up media content from your iOS device, such as music, apps, books, movies, and TV shows.
- Update your device to the latest version of iOS software.
- Restore your device from your most recent backup.
- Restart your device.
- Sync back media content from your iTunes Library to your device2.
If you are attempting to update using a Mac or PC with which you normally sync
You may see the following iTunes message:

Follow these recommended steps before updating your iOS device:
- Transfer purchases3 to your computer.
- Back up your device by syncing it with your Mac or PC first.
If you are attempting to update using a Mac or PC with which you do not normally sync
Only the content that is stored in the backup will be restored back to the device after the update is complete. Attempting to do this may result in iTunes alerting you with the following message:

If you must update your device on a Mac or PC you don't normally sync with, follow these recommended steps before updating:
- Review what is stored in a backup.
- Transfer purchases3 and sync your device with the computer you normally use.
Additional Information
Notes:
- Completing your backup may take some time, depending on the amount of content on your iOS device.
- If you are updating your iOS device on a computer with which you do not normally sync , or if you disconnect your device before the sync process is complete, you may notice that some media content that was previously on your device is no longer there. You can restore this content by syncing with the Mac or PC with which you normally sync.
- Movie rentals purchased directly from your device will not get transferred to your computer when you sync and transfer your purchases.
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