I'm seeing this with UIKit but I think it's a NSPersistentCloudkitContainer issue so will be unrelated to the UI framework.

OK, thank you. Can someone from Apple please reply to that feedback to explain how to do any of that because I'm not sure what you mean and I want an audit trail of the process. I'm a developer as a hobby, not a profession (I'm an MD), so excuse my ignorance here. Nobody from Apple has yet replied to me within the Feedback app which is why I posted this here and I see others have the same issue. My data also contains sensitive information (patient & surgical data) so I'm not keen on sending that to any third party so I need to know what to send and how to do it safely. Regards, Paul

When you said 'app container' I thought you meant the iCloud container descriptor, and 'this instrument trace' was the image I posted above (both of which I added to the feedback but clearly this isn't what you meant, sorry).

Thanks for the reply - good to know there are more of us out there. My application only seems to crash (due to RAM consumption) when the sync required is large (eg. after restoring data from an app generated backup file). It's as though it's trying to do the entire sync as a single entity instead of breaking up the cloud sync into small chunks & processing them, like it did previously (iOS 14 & iOS 15 (beta 3 & below). I think Apple is investigating this, but I've not had a formal confirmation. I tried using Code Level Support in case it was something in my code that was broken, but they said 'Apple's Investigating this' and to keep checking the Feedback app. So make sure you submit a feedback ticket! 🤓

In the iOS Simulator, the path to my store is the default location (Library -> Application Support -> xxxx.sqlite) and this has not changed since I added NSPersistentCloudkitContainer support almost 2 years ago. In fact, I've not changed any Core Data or NSPersistentCloudkitContainer code in 18 months!

Yes, happening for me on beta 7 also... however, I'll reserve judgement until Xcode beta 6 so I can see what's happening. It is possible that on my iOS 15 (beta 7) device running my App Store app that all the 'old' exports are still queued, causing the failed syncing -> crash. Fingers crossed that's the case. I'm hesitant to delete & restore all my data until I can test it in the simulator first.

So... maybe beta 8?! 😬

There does seem to be something broken with CloudKit in iOS 15 (since beta 4) in relation to background syncing and NSCloudKitMirroringDelegate getting stuck in a loop, blocking uploads from iOS 15 devices and chewing up system resources. I'm seeing this via NSPersistentCloudKitContainer. See here: https://developer.apple.com/forums/thread/687877

I'm only using the Private Database

Thanks for the update. I need to do further testing but I have seen some data (very small change) sync up from a fresh install of my app on an iOS 15 beta 8 device and down to an exisiting install with a large queued upload... which still doesn't sync (large initial persistent store) and still crashes the app. It's possible that a reset of the entire cloud store (& reinstalling the app) might be needed to clear out the 'queued' syncs on an iOS 15 beta device but I need to reserve judgement until they release Xcode 13 beta 6. I need to see that a large initial store can sync to the Development Environment first. It's next to impossible to see what's going on in my App Store app running on iOS 15 betas. I'm hopeful this will be fixed in Xcode 13 beta 6 and that resetting my private database will get everything up and running again... fingers crossed!

@talking small - Same with me. I have several entities with one-to-many and many-to-many relationships (and they can be in the thousands!). It seems that this is what causes it to suddenly swallow resources & then crash - but only since iOS 15 beta 4. It was never an issue before. It's a HUGE problem because 1) this was the whole point of NSPersistentCloudKitContainer (to get around the relationship count limit & lack of many-to-many relationships imposed by CKReferences - I think you could only have 750 from memory too), 2) I NEED to be able to ingest a large amount of data at once (external backup file), and 2) it was working just fine before! So Apple, PLEASE sort this out ASAP. I've had no communication on my Feedback report which is a little disheartening. Even a "We know it's an issue and we're onto it" would be nice. Hopefully this might be fixed with Xcode beta 6 and the reason I'm seeing an issue is because I have 'old' queued requests blocking things??

Hmm... still no Xcode beta 6. I was hoping that it would be ready before the weekend so I can do some work on my app (assuming they fix this bug). I've basically put all further development on ice since iOS 15 beta 4 and I might have to start looking at a way of warning my users before they download iOS 15 if this thing isn't fixed before release. This is so annoying and disappointing.

Any update on this? I'm feeling very despondent given the lack of communication on the issue, acknowledgement that there is an issue and that anyone is doing anything about it. If this is an iOS 15 bug (and I see no evidence that it isn't), then my users are going to be in real trouble when iOS 15 is released and it hasn't been fixed. What did Apple change in iOS 15 beta 4 that broke this??

Me too and have heard nothing back from Apple in my feedback, despite providing some of the information they needed and asking how to provide the remainder, etc. FB9412346

I wouldn't even know how to do that - I'm not that advanced!! :-D The main question I want answered is this: If it is fixed at some point, will all the changes since the last successful sync (ie. from iOS 14) sync properly or will the user's entire iCloud container need resetting?