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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

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Question marked as Best reply

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.




33 replies
Question marked as Best reply

Dec 12, 2023 7:55 PM in response to wstuart66

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.




Dec 13, 2023 6:03 AM in response to Steve A.

Steve A. wrote:

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.

The real test is when reconnecting the iPhone to the iMac for the next backup and sync...


Update - the sync process is still broken when the iPhone is reconnected having an active Apple Watch pairing in place with the watch powered on:



Resetting the Apple Watch sync data (from Watch app: Settings > General > Reset > Reset Sync Data) while iPhone is connected has no effect. The process will only complete once the watch pairing has been removed.


I can say with certainty that iOS 17.1.2 and watchOS 10.1 (or was it 10.1.1) did not have this issue - manual sync was fine. So it's a fair statement that with one of those OS's recent changes, something broke with the sync process.


Dec 16, 2023 3:58 AM in response to wstuart66

I have had the same sync problem with my macOS 14.2 and iOS 17.2 when I was trying by USB-C. 


My solution was abort synching by pull of the cable, insert again and the first thing I checked in the sync settings was "show this iPhone when on Wi-Fi". After this my syncing works correct. With or without cable.

See also here (in german, sorry): Synchronisieren von Inhalten zwischen deinem Mac und dem iPhone, iPad oder iPod touch über WLAN - Apple Support (DE)


Info: My Apple Watch series 4 (watchOS 10.2) was still paired on iPhone!


Hope that helps 😉 


Best, Tom

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.


Dec 13, 2023 12:29 PM in response to wstuart66

wstuart66 wrote:

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.


The other short-term fix I was able to pull out from other forums (and evidently, sync issues such as this did occur in the past with other iOS versions) was to force-quit the process "MDCrashReportTool" - on macOS, this can be done through Activity Monitor (Applications > Utilities). This at least will get the sync process to the tail end (i.e. sync of Contacts and Calendars) to completion. But if you choose to keep the Apple Watch paired (as I am so stubbornly doing), this is the only way to complete the sync. This process starts again each time the iPhone is connected to macOS, so it's probably best to unplug/re-plug if you have to attempt another sync via this method.


Luckily though, even by killing this process I can still manually add media to the iPhone - Music still recognizes that it's connected.


Between this and album purchases splitting randomly into multiples, iOS 17.1 / 17.2 is becoming a bug infestation...

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!

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.

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.

Dec 24, 2023 7:36 AM in response to dennis_rth

Hello Dennis. Steve A's solution to force quit the process "MDCrashReportTool" in Activity Monitor on the Mac is working for me. I've been able to sync music by doing this.

Basic steps: Start sync. When the sync reaches step 2 "preparing sync", look for the "MDCrashReportTool" in Activity Monitor. Double click it, and choose force quit. Then sync will complete.

Bad news. For me, each time I start a sync, I have to repeat the above steps. It has become a muscle memory step for me though. If you need any other help with this, let me know (I might have left out a step).

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 14, 2023 5:51 PM in response to Steve A.

I just tried my first sync with Steve A's plan to force-quit the process "MDCrashReportTool" - on macOS. I can confirm that this works, at least with my hardware configuration. I was finally able to complete a sync. At least I have (what appears to be) a workable solution until Apple fixes this. Thanks to all, and if I run across any other ideas, I'll make sure to post them here.

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

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