When I attempted to update my new iPhone 5s to iOS 7.0.2, I got an error message in iTunes that claimed there were purchased items on my iPhone that had not yet been transferred to iTunes on my Mac. It warned that I should transfer these items before updating (see image above).
This seemed a bit odd, as I did not recall purchasing any items on the iPhone since buying it. "Never mind," I thought, "Just sync the phone in iTunes and all will be well."
Wrong. The irksome message popped up when I again selected to update to iOS 7.0.2.
As it turns out, an Apple support document confirms that "iTunes Store and App Store content on your iOS device may not automatically transfer to your computer" when you sync. The article does not offer any explanation as to why this may happen (I consider it a bug, as all items should transfer during a sync).
On the plus side, the document does provide a solution: "Use the Transfer Purchases option in iTunes." To do this (as explained in another Apple support document), connect your device to iTunes on your Mac and either (a) go to File > Devices > Transfer Purchases or (b) Control-click (right-click) on the device name in the sidebar and choose Transfer Purchases from the menu that appears.
This indeed works--most of the time. Unfortunately, several people informed me that the transfer error message persisted for them even after selecting the Transfer Purchases item. What do you do then? You have two simple alternatives.
The first is to bypass the issue temporarily by selecting to update iOS from the iPhone itself, without involving iTunes on your Mac. Of course, the next time you attempt a future update via iTunes, the error message may still be waiting for you. But you can worry about that another day.
The other option is to ignore the message and proceed with the update. That's what I did.
This error is not new to iOS 7. It has cropped up occasionally for several years. However, there seems to be a resurgence with iOS 7. Although I can't prove it, I have a theory as to why.
I believe it is due to the popularity of the new Updates option for Automatic Downloads of apps, enabled via the iTunes & App Store section in Settings. This option updates apps on your iOS device in the background, saving you the bother of doing it manually. It consequently means that there will often be apps on your iPhone that are newer versions than those in iTunes on your Mac. And that's what generates the error message.
If you sync your iPhone in iTunes, versions in both locations should end up equivalent and the error should go away. Apparently, this does not always happen. However, if you additionally update apps directly in iTunes, any potential discrepancy should certainly disappear. I did this, but the error message persisted. This led me to believe that the error message itself was in error. That is, due to some sort of bug, it was incorrectly claiming that items remained untransferred. That's why I ignored the message and proceeded to update iOS.
I'm not sure what will happen the next time I need to update the iPhone's OS. But, for now, everything is working smoothly.