wstuart66 Author

Level 1

63 points

Issues with iPhone sync from MacBook after iOS17 Apple watchOS 10 to Blame

Since updating to iOS17 I have been having issues syncing my iPhone with my MacBook:

Devices involved:

iPhone 11 (iOS 17.0.3)
2020 MacBook Air M1 (MacOS 14)
Apple Watch SE (watchOS 10)

Issues:

After updating iPhone to iOS 17 issues syncing started - when trying to sync music from my MacBook to my iPhone, process gets stuck at 'preparing to sync' (I'm not using Apple Music streaming - all of my music is purchased) - I was able to work around this by unplugging and replugging in the USB and eventually it would sync.
I initially thought when MacOS was updated from macOS13 to macOS14 the problem would resolve, but it has persisted.
I've restarted both devices several times.
I've tried deleting the Music app from the iPhone.
I deleted and rebuilt my Mac music library.
I reset the iPhone and set up as a new Phone, AND THE PROBLEM WAS RESOLVED.
UNTIL I paired my Apple Watch (watchOS 10). As soon as I paired the Apple Watch the sync problem reappeared.
I un-paired the Apple Watch and the sync worked normally and as expected.

One more thing, my wife has an:

iPhone (iOS 17.0.3)and MacBook Air M1 (macOS 14)

BUT her watch is an Apple Watch Series 3 (watchOS 8.8.1 (the latest for that series watch)

and syncing from Mac to the iPhone works normally with that combination of devices/OSs.

The only difference between my devices and my wife’s is the model of watch and therefore the watchOS version.

My setup WILL NOT sync correctly while my watch is paired and hers will operate as expected with her watch paired.

THEREFORE watchOS 10 is to blame for the syncing problems I am experiencing.

I hope this helps someone and I hope it’s solved soon.

Thank you.

ps I am not able to TAG this conversation the way I want to so I hope this message is in the correct place.

iPhone 11

Posted on Oct 7, 2023 11:00 AM

Top-ranking reply

Steve A.

Level 3

724 points

Posted on Dec 12, 2023 7:55 PM

I can confirm that the problem persists under iOS 17.2 (iPhone 14 Pro Max) on macOS Ventura 13.6.3, with Apple Watch Series 6 updated to watchOS 10.2.

My iOS backups are performed locally (via USB cable) and started noticing the neverending "Preparing to sync..." (Step 3) tonight. Once unpairing my watch from within the iOS Watch app (while the iPhone was still connected and caught in this loop), the minute that the device recognized that the Watch was no longer associated with the iPhone, the sync completed normally.

I was constantly killing the MDCrashReportTool process just to get out of the sync hang, but the hang would return the next time the iPhone was connected. (the process starts itself up evidently at each connection to the iMac)

I just repaired the watch to the iPhone (albeit using the last watchOS backup found) - hoping that the fresh pairing completes the sync process. I just pressed "Sync" from the iPhone's Finder window (while iPhone still connected) and the sync performed as expected.

The real test is when reconnecting the iPhone to the iMac for the next backup and sync... (I'm a little fried at the moment, and don't have the patience to go through the unpairing steps again, just in case)

Regardless, you definitely get the upvote for detecting this! If you haven't submitted a bug report feedback submission as of yet (via https://www.apple.com/feedback/) I highly suggest you do so.

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34 replies

Dec 15, 2023 6:15 AM in response to wstuart66

I have been having problems with CarPlay (over USB) as well over the same timescale so I will now go and see if this is the problem. Unpairing the watch certainly sorted the sync problem for me.

rdmft

Level 1

10 points

Dec 13, 2023 9:35 AM in response to Steve A.

And I can confirm what Steve A. has experienced. I am using iOS 17.2 (iPhone 14 Pro Max) on macOS Sonoma 14.2 (MacBook Pro 14" 2021), with Apple Watch Series 9 updated to watchOS 10.2. My iTunes sync was left on for 14 hours, and was stuck at Step 2 "preparing to sync". I tried turning off the watch (lazy step) to see if the sync would progress, but it did not.

I will be curious to see Steve if the unpairing/repairing step with the watch corrected the sync issue, or is just a temporary fix.

And bug report completed. Hopefully Apple will correct this quickly!

wstuart66 Author

Level 1

63 points

Dec 13, 2023 10:52 AM in response to wstuart66

Thanks to all for replying and letting me know I am not the only one!

For what it's worth, the problem persists in macOS Sonoma 14.2, iOS 17.2, and watchOS 10.2.

I have submitted more than one report to Apple regarding this.

The ONLY time the iPhone will sync normally with the Mac is if the watch is NOT paired with the iPhone.

At this time I have un-paired my watch and I am not using the Apple Watch due to this issue.

Thanks again, and hopefully this gets sorted soon.

Dec 24, 2023 7:54 AM in response to rdmft

This has worked for me as well. Immediately after I force quit the process "MDCrashReportTool" during step 2, the synchronization went through without any problems. Thank you very much!

Steve A.

Level 3

724 points

Dec 13, 2023 9:41 AM in response to rdmft

rdmft wrote:

I will be curious to see Steve if the unpairing/repairing step with the watch corrected the sync issue, or is just a temporary fix.

It didn't - even if the Apple Watch is re-paired to the same iPhone, once the iPhone's USB connection is removed, it will go back into this endless sync loop the next time it is reconnected to USB.

Right now, the only way to get the iPhone to complete the sync is to not have the Apple Watch paired at the time of connection - which is hardly a solution to this issue.

On a side note, I can't run macOS Sonoma, my iMac doesn't meet the minimum specs - was curious if this whole thing may have been related to Ventura's last update. Apparently not, since you experienced the same thing running Sonoma.

Dec 24, 2023 4:29 AM in response to wstuart66

I have the same problem. I can no longer transfer my purchased music from my Mac (14.2.1) to my iPhone (17.2.1). I also use an Apple Watch with watchOS 10.2. In my opinion, the error has existed since iOS 17. I am using an iPhone 11 Pro.

Steve A.

Level 3

724 points

Jan 22, 2024 1:46 PM in response to wstuart66

wstuart66 wrote:

WOW glad to hear that and I hope it continues to work correctly.

I have given up on my Apple Watch due to these issues and use an "other" watch now, but I am glad to hear that Apple has apparently solved this (even though it's still inconceivable that this ever happened and and that this issue lasted until the point3 release!!)

Can double-confirm this - the initial sync appeared that it was still hanging in macOS, but after several minutes, the process finally completed without the need to force-quit any running processes.

This completed after both iOS and macOS were updated, but before watchOS was updated to 10.3. (that portion is running now)

Thank you for making this connection in the first place!

wstuart66 Author

Level 1

63 points

Oct 25, 2023 4:41 PM in response to wstuart66

UPDATE: 10/25/2023

This is STILL NOT WORKING, after updating all devices:

iPhone 11 (iOS 17.1)
2020 MacBook Air M1 (MacOS 14.1)
Apple Watch SE (watchOS 10.1)

My 2020 MacBook Air M1 (MacOS 14) WILL NOT sync with my iPhone 11 (iOS 17) while my Apple Watch SE (watchOS 10) is paired with my iPhone.

As soon as I UNPAIR my Apple Watch from my iPhone everything works normally and as expected.

wstuart66 Author

Level 1

63 points

Dec 13, 2023 12:33 PM in response to Steve A.

The other way I have been able to complete a sync is to plug the phone into the Mac and start the sync. When it gets stuck at “Preparing…” unplug the usb cable and plug it back in, and the sync will complete.

However it only works for that one sync and the next time you attempt a sync it will fail again and you have to repeat that process.

I am too stubborn to use a workaround and expect more from Apple, so even though I can force it to sync completely I refuse to use that method.

YMMV.

wstuart66 Author

Level 1

63 points

Dec 14, 2023 12:00 PM in response to rdmft

rdmft wrote:

Hello wstuart66. Thanks for your suggestion. One question, does the connect/disconnect increase the probability of corrupting the sync file? My main reason to sync is my music library which I keep resident on my iPhone. And I tend to make a lot of changes. For the moment I'm holding off on any syncs out of an abundance of caution. And like you and Steve A, I will keep using my Apple Watch. I have hearing loss, and I rely on it to notify me of text messages, emails and calls. Not an option to not use it...

Hello, In MY usage I have not seen any data corruption, but I can't say with certainty.

I would tend to think not though since the sync doesn't actually begin until after the cable is re-connected, so there shouldn't be any disruption in the movement of data.

The sync getting stuck at "Preparing..." seems to indicate a problem in the 'handshake' between the two devices. I wondered at one time if it was a "Trust" issue between the devices, but in any case, all that happens prior to any data syncing, and so should not cause any corruption, but as always, your mileage may vary.

Take care.

Jan 1, 2024 12:44 PM in response to dennis_rth

Hello, I have a similar problem to yours, in addition to your problem of getting stuck on preparing to sync. My main issue is that Apple Music is not syncing correctly between devices. I also think that the new OS update is the main cause of that.

I use Apple Watch 10.2, iPhone 17.2.1, macOS Sonoma 14.2.1, and iPadOS 17.2.

wstuart66 Author

Level 1

63 points

Oct 20, 2023 10:00 AM in response to wstuart66

UPDATE:

This is still not working.

My 2020 MacBook Air M1 (MacOS 14) WILL NOT sync with my iPhone 11 (iOS 17) while my Apple Watch SE (watchOS 10) is paired with my iPhone.

As soon as I UNPAIR my Apple Watch from my iPhone everything works normally and as expected.

Dec 5, 2023 10:20 AM in response to wstuart66

This is broken for me too. When attempting to sync my iPhone with my iMac Pro via iTunes, the progress gets stuck on "preparing to sync" for about 10 minutes. Then it eventually finishes and sync is completed. I can't pinpoint exactly when this problem began, but it happens every time I attempt to sync. My details are...

iMac Pro, Mojave 10.14.6

Iphone SE 3rd Generation, iOS 17.1.1

watchOS 9.6.2

Steve A.

Level 3

724 points

Dec 13, 2023 8:06 AM in response to wstuart66

wstuart66 wrote:

UPDATE: 10/25/2023

This is STILL NOT WORKING• , after updating all devices:

iPhone 11 (iOS 17.1)

• 2020 MacBook Air M1 (MacOS 14.1)

• Apple Watch SE (watchOS 10.1)

FYI - I've logged a "Report A Problem" from the Apple Watch Feedback page with as much info as we (all) have been able to determine. Let's hope it reaches Engineering sometime this month...

rdmft

Level 1

10 points

Dec 13, 2023 10:21 AM in response to Steve A.

Thanks for the info Steve, and the clarity of your explanations. This should give Apple the information they need to correct this.

I think we can safely say that the problem rests in iOS 17.2 or watchOS 10.2 (or both) since this is occurring in both of our computers which are running different operating systems.

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Issues with iPhone sync from MacBook after iOS17 **Apple watchOS 10 to Blame**