This article originally appeared in TidBITS on 2010-11-03 at 2:29 p.m.
The permanent URL for this article is: http://tidbits.com/article/11717
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An Unexpected Fix for an iPad Syncing Error

by Lex Friedman

I don’t sync my iPad all too often. It holds a charge for so long and is nearly always on a Wi-Fi network, so it’s easy to just plug it in at night, download app updates directly on the device, and forget that it can even sync with iTunes at all.

So when I have a lot of new music or other media to sync, the process can take a while. iTunes inevitably wants to back up the device—which I appreciate—and make sure everything’s in order. Recently, though, I began to encounter a decidedly unpleasant issue when syncing: an ambiguous error was halting the syncing process prematurely. Again and again, each time I tried to sync, iTunes popped up this error:

“The iPad ‘Lex’s iPad’ cannot be synced. The required file cannot be found.”

To my eyes, that error message has two defining characteristics:

  1. It’s not in the slightest bit helpful.
  2. It seems highly Google-able.

So I searched the Internet for a fix. As it turns out, the true culprit for this poorly described error is, of all things, iPhoto. Apple has a rather terse support note, “Issues when syncing photos to iPhone or iPod touch [1],” that gave me the clue I needed to fix the problem.

When you sync photos to your iOS devices, iTunes creates a hidden folder called iPod Photo Cache. That’s where it tucks away data regarding your photos to optimize them for your iPhones, iPod touches, and iPads.

The fix? Delete the iPod Photo Cache folder.

To find the folder, first quit iPhoto and then navigate to your iPhoto Library, which is located in your home folder at ~/Pictures/iPhoto Library. When you find it, Control-click it and choose Show Package Contents from the contextual menu. (The iPhoto Library is a package, which is a special sort of folder. Show Package Contents exposes its contents.)

Inside that folder, you’ll find the iPod Photo Cache folder. Drag it to the Trash. (If you don’t make regular backups—well, first, shame on you, but second, you may prefer just to drag the iPod Photo Cache to the Desktop, and not trash it right away. But the fact that iTunes can easily regenerate the cache is at the core of this fix.)

It's also worth noting that the iPod Photo Cache can contain a lot of unnecessary data; Adam Engst was having the same problem syncing his iPad, and his iPod Photo Cache folder weighed in at over 11 GB when he deleted it; the regenerated copy took up less than 2 GB. If you switch from syncing photos from iPhoto to syncing from another folder, you’ll want to remove the folder manually to recover disk space—see Apple’s “iTunes: Photo sync creates iPod Photo Cache folder [2]” support note.

Once you’ve axed the iPod Photo Cache folder, relaunch iTunes. Attach your iPad to your Mac, click its name in the sidebar, and then click the Photos button in the main iTunes pane. You need to reconfigure which albums, events, and faces you wish to sync, and when you’re done, click the Apply button to sync your iPad. You’ll see a warning that photos on the iPad will be replaced; don’t worry about it, since all the photos that are being replaced came from your Mac to start with. The sync should proceed apace (though iTunes has to optimize all your photos again, so it may take a little while), but when it’s done, rejoice: the error message will be a thing of the past.

[image link] [3]

I don’t yet understand why or when this error occurs, or how to prevent it. But the workaround is painless enough, and recurrence of the error rare enough, that I haven’t given it much thought.

[1]: http://support.apple.com/kb/TS1306
[2]: http://support.apple.com/kb/TS1314
[3]: http://db.tidbits.com/resources/2010-11/Replace-Photos.png