iPod/iPhone Cannot Be Synced, Required File Not found

This one is definitely a post in the category of primarily being a reminder for future me in case an annoying problem reoccurs, but I guess it may be useful for anyone else struggling with a similar issue.

A couple of days ago I plugged my iPhone into the Mac to synchronise it using iTunes, and after what seemed like a normal process, the process came to a sudden halt during the photo synchronisation stage with a pretty useless error stating that the iPhone could not be synced because a “required file” was not found. Needless to say it didn’t actually tell me what the required file was, nor where it was looking.

My first port of call was to have a trawl through the log files, which is where I made another annoying discovery, iTunes doesn’t seem to log details of it’s synchronisation operations anywhere.

The Mac has for a while had a nice suite of synchronisation technologies based around an application called iSync. Certainly the iPhone synchronisation uses at least part of this as if you have iSync set up it will activate during an iPhone or iPod synchronisation with iTunes. If you ran into any problems with iSync there was always a handy menu option to take a look at the log file and try and track down where it went wrong. No such luck with an iPhone as according to that log file the last time I synchronised anything was the last time I did my old phone.

Okay, what about the main system log? Although this has some messages from iTunes, there is nothing to even indicate that a synchronisation operation has taken place.

Having not come up with anything I then reverted to the usual source of information for weird errors, and googled the error message. That produced plenty of people with the problem, but nobody with much of a clue as to how to solve it.

I figured that since iTunes was drawing the pictures from iPhoto, that might be the source of the problem. Certainly that had changed in between the last successful synchronisation and this attempt in that Beth had loaded all of her pictures from our recent trip into the application, but looking through those there wasn’t anything out of the ordinary amongst those. I used the iPhoto maintenance mode (hold down the command and option keys when you start the application) to rebuild the iPhoto database, but again that produced the same problem. A friend suggested that the presence of movie files in the albums being transferred might be an issue, so I tried removing those, but again no joy. The only way I could get anything to properly transfer was to remove the albums that contained Beth’s newly uploaded pictures.

Last night I finally got to a solution. In all my removing and replacing pictures, and even after I had rebuilt the iPhoto database iTunes had never been through the long and rather tedious “Optimizing pictures” stage. Digging around I found that these were stored in a folder within the iPhoto database called iPod Photo Cache – the key thing being that the contents of this folder are not regenerated by an iPhoto database rebuild. So last night I tried deleting the folder as advised in this Apple Support Document (which incidentally is nowhere to be seen when you search for the actual error), and then left the iPhone synchronising overnight. Based on the speed it was going the optimisation phase would have taken about five hours – certainly the computer had not yet reached it’s inactivity timeout, however all the photographs had successfully transferred.

So for future reference, if iTunes starts throwing useless error messages whilst synchronising photographs, take a look at the iPod Photo Cache, and if necessary delete it. One last thing, can Apple Inc please consider adding some sort of logging functionality to the iTunes synchronisation function as we have for regular iSync, then at least we have a vague hope of tracking down errors rather than playing vague guessing games!

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34 thoughts on “iPod/iPhone Cannot Be Synced, Required File Not found”

  1. Wow apple is ridiculous sometimes! Thanks this worked perfectly for 3gs. Now if only apple could provide it’s own troubleshooting that would be amazing.

  2. I tried all this. But error persisted. My workaround was to export the album I wanted on iPhone, import it into library, create a new album and then sync'ed that album only with iPhone.

    I may revisit this – because I think it is the optimized images that are screwy – but I deleted the folder (and emptied the trash) twice but it did not fix.

  3. THANK YOU!!!!! I have been trying almost everything you said in this PERFECT explanation but never even thought about the iPod photo cache! YOU ARE AMAZING!!!! If I could hug you i would! 😀

  4. Hi,

    perfect – thougt about sth like that! the reason why this happend to me was a full clean with “Clean my mac”. this Programm removes all cach files to gather more file space on your disk!

    Be aware with http://macpaw.com/cleanmymac good software, but can lead you in a bad situation with iPhone Photo sync


  5. I have the same problem. I also could not find the iPod Photo Cache file (not sure if this is a windows vs Mac difference, mine being a Mac). So I resorted to doing the export of the photos and then reimporting them back into the folder I use to sync with the iPhone.

  6. The solution for me was even simpler: sync the phone without syncing photos (choose “Remove Photos” in the dialog box that’s offered), and then check the “sync photos” tick box and re-sync. Done and dusted.

  7. This still works in 2011. Like you said it’s the iPod Photo Cache FOLDER and once deleted my problem was gone. I don’t even have iphoto as a photoshop user I don’t need it, and I have a folder where I put portfolio pix I want on my iphone. There was the offending folder and once deleted, it itunes made a new one and all was well. 2 thumb up man!

  8. Thank you, thank you, thank you! Deleted iPod photo cache folder(s) – I had 3 folders, and it was my iPhone that wasn’t syncing – and the problem is GONE! W00t!

  9. Oh THANK YOU! This helped me with my problem in a fraction of the time it took you to figure out. You are a generous person and I appreciate the additional time you took to type up this explanation and include helpful links!

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