Skip to main content

Apple delays support for iOS 9 ‘App Thinning’ feature due to iCloud backup bug


Apple has announced that one of iOS 9’s big new features, App Thinning (or “app slicing”), has been delayed due to an issue with iOS 9. App Thinning was announced at WWDC as a way to help trim down the size of large applications by letting developers mark assets for each specific type of device. When users download the app, the App Store will determine which device they have and only require them to download the assets necessary to run on their device.

While TestFlight has supported the feature for a few weeks, Apple says the public version of iOS 9 will not support it until a later update due to a problem with the way iCloud handles backups.

The issue was explained in a post on Apple’s developer center.

App slicing is currently unavailable for iOS 9 apps due to an issue affecting iCloud backups created from iOS 9 where some apps from the App Store would only restore to the same model of iOS device.

When a customer downloads your iOS 9 app, they will get the Universal version of your app, rather than the variant specific for their device type. TestFlight will continue to deliver variants for your internal testers. App slicing will be reenabled with a future software update. No action is needed by you at this time.

This may explain why many app updates that were released over the past few weeks have been mysteriously reissued by Apple since yesterday morning, though the company hasn’t confirmed the connection.

App Thinning will continue to function on TestFlight without any changes, but developers will not be able to distribute sliced versions of their apps on the App Store until a software update fixes the issue.

FTC: We use income earning auto affiliate links. More.

You’re reading 9to5Mac — experts who break news about Apple and its surrounding ecosystem, day after day. Be sure to check out our homepage for all the latest news, and follow 9to5Mac on Twitter, Facebook, and LinkedIn to stay in the loop. Don’t know where to start? Check out our exclusive stories, reviews, how-tos, and subscribe to our YouTube channel


  1. chrisl84 - 8 years ago

    iCloud backups are all messed up for me and some other people I know, keep randomly saying the last backup was: “Never”…..which is wrong, and often doesn’t list the backup in manage storage section.

  2. brianskoog - 8 years ago

    Not sure if its the same issue, but when I restored the backup I created on my iPad 4th Gen to my new iPad Mini 4, forScore, Twitterrific, and 1Password didn’t make it over.

  3. TfT_02 - 8 years ago

    This is one of my favorite features of iOS9 !

  4. Robin Keanu Keim - 8 years ago

    My heart goes out to anyone who bought a 16GB iPhone 6s today…

  5. calisurfboy - 8 years ago

    Pretty common problem for the past few years for Apple to offer features that are delayed or broken for months on end. Reminds me of how AAA video game companies are over-promising on games and shipping broken titles.

    • elilabes - 8 years ago

      Which is why they pulled it from release, they could have just launched it broken like as you say some AAA video game tittles do. BUT they didnt which sets them apart. It looks like they finally learned from there mistake of launching apple music well before it was ready with no shuffle and multiple streaming problems which are only just being sorted out today.

  6. Vlado Bízik - 8 years ago

    What about existing app installations? When App Thinning is launched, will iOS (perhaps during an update) automatically delete the unnecessary app components or will one have to re-download the app?

    • totencough - 8 years ago

      In theory, you should just be able to update to the new version that includes App Thinning, and it should only include the required assets for your device.

      In theory…

    • AeronPeryton - 8 years ago

      All apps would have to issue an update to turn that feature on. There will have to be some architecture retooling so that yanking random parts out doesn’t utterly break the program.

  7. hydrovacing - 8 years ago

    Apple has to stop announcing new features until they work. Makes themselves look like a bunch of bumbling idiots.

    • AeronPeryton - 8 years ago

      They announced App Thinning at a developers conference. Developers need to know about new features long before they actually ship so they can be ready to use them when they are ready. It’s just that Apple suffers from that developer conference being highly publicized to the public at large …and all the cons that come with it.

  8. Gort (@DrugstorCowboy) - 8 years ago

    Good. I am glad Apple is doing this. Seriously. Instead of bowing to media pressure, Apple is showing guts by saying no, and not making a mess of things by trying to please everybody. Better to wait and get it right, and get it wrong.

    That said, I am expecting that slime ball Luddite and Apple hater Henry Blodgett to run yet another cheap shot story about this in his tabloid POS website Business Insider. Because that’s what he does. Of all the shameless click-whoring scum out there, Blodgett tops the list.

  9. Charlypollo - 8 years ago

    So many bugs and problems with the latest IOS in both the watch and the phone. So many delays, broken features or plain even malfunctions. Apple is losIng itself in its own success.

  10. iSRS - 8 years ago

    I agree it is good they pulled it. Also quietly missed is support for store credit cards and gift cards in Apple Pay. Haven’t heard a thing about them.

    I wonder how long they can keep up this annual pace. Maybe alternate major updates between iOS and OS X.

    There are too many fantastic ideas that aren’t quite fully baked. Glad they are, if the rumors are true, working on their back end web services

  11. What if the app is downloaded using iTunes on Mac? Will it download two version (one for iPad and iPhone each)?

    • Alessandro Gaietta - 8 years ago

      The same I am trying to figure out, as I usually download them from iTunes on PC. Another question is when you donwload them from the device (thinned), sync with the PC/MAC, then you change device and restore a backup, at that point iTunes re-install all the .ipa from the PC/MAC library, which should contain only the resources for your old platform…

    • iSRS - 8 years ago

      From what I understand, it is the process of loading to the device that trims it. So assume it will download the whole thing (Apple TV as well)

  12. Hubert Johnson - 8 years ago

    So, should we be (re)installing all these re-issued updates? Between my wife & I we have 4 devices, which equals well over a hundred updates. I find it unbelievable that a Corp like Apple could violate such a fundamental concept – you cannot re-issue something using the same date and ver numbers, and change the code! That’s like reissuing yesterday’s newspaper with yesterday’s date, but with different news in it.

    • iSRS - 8 years ago

      That isn’t what is happening. Every new iOS update (7,8,9) is followed by a ton of app updates.

      • Hubert Johnson - 8 years ago

        Yes, I am aware of that, but that’s not what is happening, at least to me. As I said above we have dozens and dozens of apps showing up in the App Store with the Update button. The dates on these “updates” range from yesterday back to the middle of September. The version numbers are unchanged from when they first showed up (on those dates) and were all installed. For example, I have Microsoft Outlook on my iPad. An update showed up last week (Sept 17 specifically) to update it to ver 1.4.3; I did so. I subsequently updated to iOS9, then 9.0.1. A couple days ago, lo and behold an update notice shows up in the App Store for Microsoft Outlook – dated Sept 17 and ver 1.4.3. If I was to click on the update button, it would dutifully go through the motions and look like it was installing it, just like it did the first time. This is the same as with all the dozens of apps currently sitting their with Update buttons beside them. When this first started happening a few days ago, I went ahead and clicked on them and updated. But now I am not so sure that is the right thing to do.

      • Hubert Johnson - 8 years ago

        Here is screen shot of the Updates tab on my iPad. Every one of those “updates” was already installed, almost without exception on the day they came out.

  13. capdorf - 8 years ago

    Went for a walk today. Used my iPhone 4s as a stop watch ( updated to ios9 last night ) Don’t wear my glasses when walking, which makes some difficulty reading, since ios7. Hit the button to reset then the button to start. It was all wrong. Had a closer look, l had got the buttons in the wrong order, strange.
    Got home, compared it to my old iPod ( old iOS easier to read) ….. APPLE HAS REVERSED THE BUTTONS… WHY??