Earlier this week, iTunes on my Mac encountered an issue that wouldn’t allow it to sync normally. The error message read “This computer has been previously synched with an iPhone or another iOS device” and asked whether I wanted to either “Setup as a new iPhone” or to “Restore from a backup.” I didn’t want to select the second option because I backup my iPhone to iCloud, and the backup on my Mac was several weeks old and useless.
This is the same problem that Michael Williams encountered and blogged about in August with iOS 5 beta. He suggested a tricky workaround: initiating a restoration and then yanking the USB cable from Mac when that process starts. That causes the sync to fail and, after iTunes chides you for disrupting the restoration, it reestablishes the normal synchronization process.
When I tried to follow this process, I got a different but equally effective result. First, I backed up to iCloud to ensure that if iTunes wiped my phone in order to restore it, I would have a very recent backup. Second, when I initiated the restoration, iTunes did not actually try to restore the phone. Instead, it performed a normal sync, and all seemed well. The only issue was that it restored all of the apps I had once downloaded but since removed from my iPhone. (I had done so because I was trying to stop the infamous iPhone’s battery drain that many users encountered after upgrading to iOS 5.)
Based on the commentary on other blog posts, it looks like this might be a side effect of WiFi sync. However, I have also been doing that with my iPad since the release of iOS 5, and nothing like this has happened with that device.