Sync Services: Advanced troubleshooting for contact and calendar syncing

1. Open Address Book. Back up your contacts by choosing Export from the File menu and selecting Address Book Archive. Specify an export location and then click Save. The resulting archive file will contain a backup of all of your contacts information that you can restore later into Address Book (if necessary) by double-clicking it in the Finder.
2. Remove any duplicate or unnecessary blank entries by following the procedure outlined here. It may be necessary to repeat this procedure until duplicate entries no longer appear.
3. From the Address Book menu, choose Preferences and click the vCard tab. Ensure the 3.0 option is selected for vCard Format and that both the “Export notes in vCards” and “Export photos in vCards” options are selected.  
4. Create a new folder on the desktop. Select all of the contacts in the Name category in Address Book by choosing one of them and then choosing Select All from the Edit menu.  Next, drag all these contacts into the new folder on the desktop by clicking and dragging one of the highlighted names; this will result in one vCard generated with all your contacts.
5. Open iSync, then choose iSync > Preference and deselect the option to "Enable Syncing on this computer."
6. Delete all of the contacts and groups in Address Book. Quit Address Book.
7. Move the following files to the Trash:
   • ~/Library/Application Support/Address Book
   • ~/Library/Preferences/com.apple.AddressBook.plist
   • ~/Library/Preferences/com.apple.AddressBook.abd
8. Drag the files located inside both of these folders to the trash:
   • ~/Library/Caches/
   • /Library/Caches
9. Log out of your user account.
10. Log in to your user account. Open iSync and then choose iSync > Preferences > Advanced > Reset Sync History. Then, select the option to "Enable Syncing on this Computer."
11. Open Address Book. Drag the vCard from the folder you created on your desktop to the Address Book window to re-import them. To re-create contact groups, create the groups first in Address Book and then drag the appropriate vCards to each group.
12. Attempt to sync normally using iTunes for your iPhone, iPod, and iPod touch, or use iSync for other mobile devices.
13. If the contacts still do not sync, try starting your computer in Safe Mode by pressing and holding down the Shift key after hearing the chime on startup. It may take several minutes to start your computer in Safe Mode. After starting in Safe Mode, restart your computer and then attempt to sync normally.  
14. If your contacts don't sync, consider contacting AppleCare for support, or see this article for more information about removing the Sync Services folder. However, removing this folder is strongly discouraged, and should only be performed when the syncing Mac has been started in Safe Mode.
15. Once your contacts and groups sync correctly, create a new backup of your contacts, using the procedure outlined in step 1. This will preserve any of the changes you made that fixed your sync issue.

1. Back up your calendars by following the steps in this article. You can also choose Back up iCal from the File menu in iCal if you're using Mac OS X v10.5 Leopard.
2. Quit iCal. In the Finder, delete the Calendar Cache files including any that also display a -1, -2, and so on directly after their filename. You can find these files in ~/Library/Calendars/Calendar Cache.
3. Drag the files located inside both of these folders to the Trash:
   • ~/Library/Caches/
   • /Library/Caches
4. Open iCal. Attempt to sync normally using iTunes for your iPhone, iPod, and iPod Touch, or use iSync for other mobile devices. If the sync does not work, attempt to sync only one calendar at a time, noting which calendars do not sync.

Before continuing to step 5, If the issue is isolated to specific calendars, follow the expandable steps below (organized by operating system) to try to locate event titles that could be problematic during sync troubleshooting. Check your event titles for the following:

• Check to see if any calendar events have blank or empty titles. If so, rename these events so they have a title or delete the event.
• Check for calendar entries containing any events using high ASCII or double-byte (Unicode) characters in the event title (such as Japanese, Chinese, Korean or other extended ASCII characters). Try removing these characters or substituting them with non-extended ASCII characters.
• Check for and remove any duplicate calendar entries.
• Consider removing some old events if you have a very large number of them.

Using Mac OS X 10.5

Using Mac OS X 10.4 and earlier

5. Open iSync, go to iSync > Preferences and deselect the option to "Enable syncing on this computer."
6. Remove all the calendars in iCal.
7. Open iSync and then choose iSync > Preferences > Advanced > Reset Sync History.  Then, select the option to "Enable Syncing on this Computer."
8. Using the backup you created in step 1, import one calendar into iCal by choosing Import from the File menu. Verify that you can sync this calendar.
9. Continue to import and sync one calendar at a time until all of them sync successfully or you discover one that does not sync.
10. If your calendars still don't sync, consider contacting AppleCare for support, or see this article for more information about removing the Sync Services folder. However, removing the Sync Services folder is strongly discouraged, and should only be done when your computer has been started in Safe Mode.
11. Once your calendars sync correctly, create a new backup using the procedure outlined in step 1. This will preserve any of the changes that you made which fixed your sync issue.