So, yesterday @Prepressology got his iPhone and I was trying to sync mine and it keep giving me an error. I forgot about mine and played with the 3GS and let my troubles rest. This was what was happening:

Every time I wanted to sync, I got a scary warning from iTunes:

The iPhone cannot be synced the required file cannot be found

Yes, I was scared! I tried restoring from a backup, resetting. Everything. By Monday night I was ready to give it a rest. So, Tuesday morning after a nice cup of coffee, decided to fix it.

First, I discovered that when I stopped syncing some of the iPhoto’s smart folders, I kept getting the error. The problem was not  on the selected smart folders, it was the syncing from iPhoto that was the trouble. So, I rebuilt the Photo Library (Versions 6 and up)

1. Quit iPhoto (if it is open)
2. Hold down the Command and Option keys on the keyboard.
3. Open iPhoto.
4. Keep the keys held down until you are prompted to rebuild the library.
5. A dialog will appear with rebuild options. Select the options you want to use.
6. Click Rebuild to begin the rebuild process.

This may take a few minutes to complete, I have a decent sized iPhoto Library and it took about 4 minutes.

After that, you need to empty the iTunes’ iPod Photo Cache folder. What good does it do that you rebuild iPhoto’s Library if the cache syncing back and forth with your phone is damaged? Doing this won’t damage any of your pictures on iPhoto. Deleting this folder will force iTunes to create a fresh cache folder. To do so, you need to:

1. On your Home folder, locate the Pictures folder and locate the iPhoto Library file.
2. Control-click the iPhoto Library file and choose Show Package Contents from the shortcut menu.
3. In the iPhoto Library window, locate the iPod Photo Cache folder and drag it to the Trash.
4. Close the iPhoto Library window.

If you’re a bit nervous to empty the trash before the sync, it’s Ok.

Now, try syncing your iPhone with the iPhoto selections that you want transferred and voilá! You can empty the trash now 🙂