∅ the empty set

.Mac calendar synchronisation problem in Leopard


I've been having synchronisation issues with .Mac services recently related to my iCal calendars. Usually, resetting the .Mac copy with a local copy from one of my computers solved the problem. But not this time.

The SyncServer was generating errors like:

iCalExternalSync[823] [ICalExternalSync ]NSException name:NSInvalidArgumentException reason: [ISyncConcreteSession clientAcceptedChangesForRecordWithIdentifier:formattedRecord:newRecordIdentifier:]: you can't change the record identifier from 24A0D606-9C62-498A-80BF-0139313AA98D to node_LocalCalendar/p1: it is already associated with a different record.


|Error|Problem encountered while merging changes in Sync Engine: you referenced the following records (in a relationship) but did not actually push them: ( "08C4CB22-E92D-4CB5-8C1B-3EDA9E2E11F5", "0EDD7D55-9B30-43D7-BA88-84448FAB8FB9", [..]

Until the calendar synchronisation stopped all together. A dialog box told me that the data was inconsistent, and needed to be reset on .Mac.

"Calendars could not be synced due to inconsistent data. Confirm that your computer's data is valid, then reset Calendars on .Mac in System Preferences."

Fair enough. But it didn't solve the problem. Sync still wowed. I restored a backup copy of my calendars, and that didn't do the trick either. I restored a backup copy of another of my computers. That failed too. This was becoming irritating to say the less. At this point, the synchronisation was running on an hourly basis, but the calendars weren't being synched, and I wasn't being told.

To cut a long and boring story short, here's a workaround that worked for me: you need to start fresh again - really fresh. Wiping out all traces of previous synchronisations, caches, etc. Apparently there was some kind of discrepency in my SyncServer cache. Meaning I had to:

  1. Quit all applications that use .Mac (Address Book, iCal, iSync, Mail, Safari);
  2. Turn off .Mac syncing and unregister all computers in System Preferences;
  3. Issue the following commands from the terminal:
    killall SyncServer cd ~/Library/Application\ Support mv SyncServices SyncServices-old killall SystemUIServer
  4. Turn on .Mac syncing in System Preferences and click "Sync Now".
  5. When a dialog appears asking whether to merge or replace data on .Mac, select replace all data on .Mac with data from the computer.

You need to perform this on all your registered computers synching on .Mac except point #5: replace your local data with the fresh copy you just uploaded. My logs activity calmed down after that, no more errors. Sync bliss.

This workaround comes essentially from various Apple Discussions thread such as:

Ø permalink: https://davidroessli.com/logs/2008/01/mac_calendar_synchronisation_p/

Reponses to “.Mac calendar synchronisation problem in Leopard”

#1 by Thomas Bohmbach, Jr.

00:18 on 18 February 2008

Thanks for the great instructions. It only took me 15 minutes to fix this problem because of your post. It also saved a new computer buying experience from going bad.

#2 by Tim Quigley

03:25 on 19 February 2008

This worked for me. Thanks for the advice.

#3 by Stefanie Herzer

04:27 on 18 March 2008

I was just running into the same problem but after reading this post I was able to fix it in 1 minute.

I simply re-created the calendar data from my main machine (which holds the most up to date calendars) overwriting the old calendar data on .Mac. I just used the regular advanced feature for that. Afterwards I was able to sync the re-written calender data onto my MacBook PRO.

While this may not work for everybody it is a fast thing to try before you hit the command line purging this manually.

Hope this may be helpful for some

#4 by Ricky Nelson

19:42 on 28 April 2008

Just wanted to add that these instructions also cured my sync woes as well. I have an iMac and recently also purchased a MacBook. Some stuff synced over to the MacBook but some did not, specifically bookmarks and calendars. After following these instructions now everything is merrily syncing along. Thanks for the great post!

#5 by Patrick

11:41 on 13 August 2008

This worked, and I was finally able to sync my damned calendars after following these instructions. Thanks!

#6 by Rob Carnegie

21:08 on 4 September 2008

Yeah baby! After weeks of monkeying around with this and getting nowhere with Apple Support... This fixed my issue!
Thanks a million!

#7 by David Roessli

09:56 on 5 September 2008

Glad it worked out for you @Rob

#8 by Joseph Ryan

20:50 on 11 September 2008

I've got six devices (two each Macs, iPhones and iPod touches) I like (have to) keep in sync and since Sept 2 syncs for calendars and contacts have been failing (silently). Since I discovered this three days ago, Apple support has been getting nowhere. While waiting for them to do "research" I've been doing my own and found this work around which matches my pronlem. There may be a better solution but I am not sure Apple Support will be offering it soon. I'll post the results.

#9 by Greg. Dodwell

07:07 on 27 September 2008

I've got a similar problem: just the other way around.

I have erased all the contact and calendar data on my computer and am trying to update my iMac's iCal and Address Book from Mobile Me. My iPhone and Mobile Me are syncing wonderfully; I consider them both up-to-date. Any clues?

#10 by David Roessli

07:25 on 27 September 2008

@Greg: strange. I have always had success in updating my Mac from the online (.Mac or MobileMe now) version, if the latter isn't corrupted. Which isn't the case if your iPhone and MobileMe account are syncing okay.

Have you updated the .Mac System Preference? It should read MobileMe now (Are you running Leopard? 10.5.x?)

There were some issues with 10.4 (Tiger) and MobileMe syncing - not sure if they are resolved now.

Not much help - sorry…

#11 by Greg. Dodwell

14:24 on 29 September 2008

@David: I've updated the MobileMe System prefs several times ... I'm running 10.5.5. I've completely erased my iSync device list, as I no longer need to sync my trusty SE600i via Bluetooth (which was a painless and reliable process >_

Taking a superficial look at the solutions, my safest bet would be to copy --by hand-- my calendars and contact details from the phone to the iMac; as the trend in the posted solutions is to "sync from scratch" online from the "definitive" copy on the computer.

I'm also tempted to leave things as they are for the moment, as the iPhone/MobileMe relationship is so healthy. Not happy that my iMac can't join in as a third party!

Also, I may have to reinstall OSX --again-- as I've just finished trouble-shooting some nasty wireless networking problems. This may give me a clean slate once I re-establish my, my wife's files/account status etc.

#12 by Gilliss

07:40 on 19 November 2008

I have Greg's same exact problem. The good data is on mobileme and my iphone, with healthy syncing between the two. But my iCal in OS X 10.5.5 is way out of date and I'd just like to replace it with what's on mobileme. Yet I get the "inconsistent data" message when I try to reset data from mobileme. Annoying.

#13 by Robb Allan

00:57 on 26 November 2008

#14 by rik

19:07 on 14 December 2008

Thank you!!! It solved a problem I had since months and Apple did not help at all.

#15 by Danielle

02:30 on 19 December 2008

woohoo!!! After trying other suggestions to no avail, I am extremely pleased to say that this fix did actually work for me. Thanks so much!

#16 by David Roessli

06:30 on 19 December 2008

@rik and @ Danielle I'm very happy it worked for you. I haven't run into any similar problems since - touch wood.

Thank you for letting my know :)

#17 by Chad

20:06 on 3 May 2009

I have had the same problem with a small twist. All of my data is in the cloud on mobile me. There is no copy on my computer. How can I make a backup off of mobile me and then work off of the backup to my local machine. I am running 10.4.11 on one laptop and tower and 10.5.6 on my mac mini. HELP!!!!!!

#18 by David Roessli

11:35 on 4 May 2009

@Chad: If I understand you correctly, you need to synchronise your Mac with the data on Mobile Me, replacing the relevant data on your computer (calendar, bookmarks or whatever) with the data in the cloud.

You should find the information you require on Apple's website:


Hope this helps.

#19 by Jan W

22:48 on 28 June 2009

Hooray! Stefanie's quick solution (in posting #3) was enough to fix my problem. I encourage others to try that one out.

#20 by Lisa Cooper

07:08 on 7 July 2009

Bless you Stephanie! Weeks of stress, resolved in a quick minute.

#21 by Enrico

07:31 on 7 July 2009

Hooray! Also for me Stefanie's quick solution (in posting #3) was enough to fix my problem. I encourage others to try that one out.

#22 by Michael Schrader

19:22 on 7 October 2009

thanks a lot for your writedown, worked perfect for me!

Michael, Hamburg

#23 by David Roessli

18:22 on 9 October 2009

@Michael you're welcome - glad it worked out for you :)

#24 by Danny Thompson UK

15:58 on 28 February 2010

I had this same problem with Contacts [only].

Stephanie's post in #3 above worked for me also. I had tried a number of steps in the Apple forums.

My mistake, I believe, is in my reluctance to replace the MobileMe data in the cloud with the data that was on my Mac Mini [Snow Leopard] (my "sync/push server"). The Mac Pro (Leopard) silently stopped synching Contacts with the rest of my stuff - iPhone, Mac Mini, Macbook Pro.

Using Stephanie's one minute suggestion I have resolved the problem. Had that not worked then I'd have had to run through the full solution in this blog.

Thanks very much all. It has saved me days of grief :-)

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