Symptoms

You may need to reset the SyncServices folder if a particular Mac OS X (v10.5.6 or later) user account is experiencing one of the following issues (while another user on the same computer works as expected):

Note: Resetting the SyncServices folder is not an appropriate troubleshooting step to solve MobileMe Calendar sync issues. Instead, please see Troubleshooting MobileMe Calendar issues.

• Unable to click the Sync pane in MobileMe Preferences (in System Preferences).
• Unable to reset data on your computer with data from MobileMe.
• Unable to open or use the Sync menu.
• Unable to open iSync in a particular Mac OS X user account.

Resolution

Important: Manually removing the SyncServices folder is strongly discouraged because this may lead to unexpected data loss.

Important: Prior to resetting the SyncServices folder, it is strongly recommended that you back up any important data which you sync regularly.

• For information about backing up in Mac OS X, see this article.
• For information about backing up your MobileMe Sync data, see this article.
• For information about manually backing up Sync-related data, see this article.

Choose your operating system for steps to reset the SyncServices folder:

Mac OS X v10.6 Snow Leopard and OS X Lion

Mac OS X v10.5

Re-enabling sync-related settings after resetting the SyncServices folder in Mac OS X (v10.5.6 and later)

After you have reset the SyncServices folder, you may need to re-enable some Sync-related settings. Resetting SyncServices resets your Mac OS X User Account’s Sync settings and any local history of updates and changes to Sync-enabled data. It won’t change your current data sets, but it does delete the history of how the data arrived at its current state and disables some Sync-related settings. Here are a few things you should check and may need to turn back on if you plan on using them with Sync again:

• If you are syncing with an iPhone, iPad, or iPod via USB and iTunes, you will need to re-enable any settings for syncing data in iTunes, such as Bookmarks, Calendars, Contacts etc. You can check these settings in iTunes the next time you plug your device into your Mac.
• If you are syncing Mail Rules, in some cases Mail Rules will become deselected. Your Rules are still there, but you will need to re-enable any Rules you wish to use actively by selecting the checkbox next to them in theRules pane of Mail Preferences.
• If you are syncing with MobileMe, you will need to re-enable MobileMe Syncing in the Sync pane of the MobileMe System Preference.
• Mac OS X will see your next sync as the first sync ever in your User, so you the next time you sync with MobileMe or via iTunes, you will most likely see a dialog asking if you would like to: Merge Data, Replace Data on MobileMe/Device, or Replace Data on your Computer. In general, Merge is the default behavior for this dialog and is the preferred choice on first sync, unless you have a specific reason to choose one of the Replace options.

Additional Information

The SyncServices folder (~/Library/Application Support/SyncServices) is a key component of syncing in Mac OS X Leopard, Snow Leopard, and Lion. This includes syncing with devices and with MobileMe.