iCloud Sync not working with iPhone, works fine for Mac.

App & System Services iCloud & Data CloudKit

Created 6d

Replies 26

Boosts 12

Views 4.4k

Participants 17

I've been working on an app. It uses iCloud syncing. 48 hours ago everything was working 100%. Make a change on the iPhone it immediately changed on the Mac. Change on the Mac, it immediately changed on the iPhone. I didn't work on it yesterday. I updated to iOS26.4 on the iPhone and 26.4 on the Mac yesterday instead.

Today, I pull up the project again. I made NO changes to the code or settings.

Make a change on the iPhone it immediately updates on the Mac. Make a change on the Mac, nothing happens on the iPhone. I've waited an hour, and the change never happens. If you leave the iPhone app, then return, it updates as it should.

It appears that iCloud's silent notification is to being received by the iPhone. Anyone else having the issue? Is there something new with iOS 26.4 that needs to be adjusted to get this to work? Again, works flawlessly with the Mac, just not with the iPhone.

Boost

Alanrick OP

Wish I'd reported this weeks ago when my iPad showed this symptom on the iOS beta, but I'd assumed it was due to me using a sandbox user since Apple was so bullish in their WWDC 2023 video about the number of test cases they'd created for CkSyncEngine.

I'd also created a feedback before discovering this thread (FB22344526)

Easy to reproduce - the Apple sample app fails. Hoping it gets taken seriously.

Jeko OP

I'm experiencing exactly the same issue since upgrading to iOS 26.4 with the same code, and it's also blocking Live Activities updates. I'm also having issues on tvOS 26.4, which uses CKSyncEngine.

J0hn OP

We should not be expected to all file feedbacks for Apple to fix a critical bug that should not have shipped in the first place.

CloudKit is opaque and difficult enough to implement and test that there is sometimes no way to know if we are at fault or if it’s some quirk of the system.

Only apple could have caught this bug with certainty and they should be performing a root cause analysis about why it shipped at all. Apple’s own sample app fails. Why is that not an automated test?

Alanrick OP

I’d like a robust dev environment for this.

I’m not confident cksyncengine works for sandbox users.
I’m not confident cksyncengine works in Xcode simulators
I’m not confident cksyncengine works in development as opposed to production iCloud.

Without this confidence it’s difficult to set-up, difficult to test and difficult reporting bugs.

Jaanus OP

I am seeing zero CloudKit pushes delivered on iOS 26.4. Filed FB22367981

DTS Engineer OP

Apple

Thank you all for filing the feedback reports, which do help. If possible, would you please verify with iOS 26.5 beta (23F5043g) to see if the issue goes away, and update the status here? Thanks again!

Best,
——
Ziqiao Chen
 Worldwide Developer Relations.

DarkMouse OP

I just updated my iPhone to 26.5 beta. The syncing is now working on the iPhone. I have Mac, AppleTV and iPhone all running at the same time, and any change to SwiftData on any of the 3 devices immediately updates on the other 2.

Alanrick OP

I can confirm my App works again (iPad 26.5 beta) .✅

⁇ I cannot confirm the apple example program works as I've run out of devices (and I'm not sure if CkSyncEngine behaves properly with sandbox users or Xcode simulation)

paulr64 OP

Appears to be working on 26.5 beta

zulfishah OP

The issue isn't just with CKSyncEngine. I have a custom CloudKit-based syncing setup, which uses CKRecordZoneSubscription to listen and respond to changes in a zone, and the remote notifications aren't working with that either. I filed FB22380044 ... hopefully this can be patched up with a quick update, as it would break so many apps

Impy OP

11h

This seems to also be preventing syncing of Passwords.app inc shared passwords.