Items disappear from the Dock -- recreate account

Tuesday, July 22

Some users have run into a problem where applications refuse to stay in the Dock. When the issue manifests, dragging applications to the Dock result in persistence for a few moments, but disappearance soon afterwards. This seems to be most prevalent with Safari. In essence, the Dock appears to be refusing to accept certain applications, resorting to treating them as un-docked applications at all times, even after a reset of dock-related preferences and other system files.

Apple Discussions poster joelinho writes:

"I have tried deleting the dock.plist and dock.db files. After I restart, the default collection of dock items appears, including Safari. Seconds later, however, [Safari] disappears."

The direct cause for this problem is unknown at the moment, but it seems to be related to Apple's synchronization features, which handle some of the affected applications: Dashboard, Dock, and Safari. Regardless of the root cause, the problem appears to be with the user account as opposed to the system itself, and the solutions so far have been to either recreate the user's account, migrate to a new one, or as a last resort reinstall the operating system.

Fixes

Remove Dock related preferences first Ensure first and foremost that this problem is not just related to dock preference corruption, by going to the ~/Library/Preferences folder and removing the com.apple.Dock.plist and com.apple.Dock.db.plist files. Then logout and log back in (or open the terminal and type "killall Dock") to recreate the dock preferences. If the problem is fixed at this point, then the problem was due to corrupt preference files and no further action is needed beyond setting up and customizing the Dock again.

Recreate the user account Log into another administrator account (create a new one if needed), and then go to the "Accounts" system preferences. From there delete the problematic account and be sure to choose the option to save data and settings for the account. This will keep all the data from the account in a disk image file located in the "Deleted Users" folder for access later on. After this is done create a new account with the same username and password as the previous one, giving it the same administrative privileges as before, and log into it.

When the new account is set up, copy the data files from the old account to the new one (Music, Documents, Pictures, etc), but leave the contents of the Library out. For applications that are used frequently, locate resources within the library (mainly preference files) and copy them to the new account. Be sure to log out and log back in after every file (or small batches of files who's origins are traceable) that is copied from the previous library, to ensure the problematic behavior does not come back. If everything is fine then continue repeating this process until all needed library items are transferred to the new account.

Migrate to a new user account Similar to the first fix, creating a new account with a new name can also work. In this case, however, it may be desirable to leave all previous library data with the old account and start fresh, perhaps only copying data-like items such as mailboxes and leaving preference files alone.

Reinstall the OS While it appears that this problem is located within the user account, it is possible some faulty system setting could cause the problem as well. In this case migrating accounts will not work, and the most straightforward solution would be to reinstall the operating system. Unfortunately preserving user accounts may not help the situation, but by using "Archive and Install", all user data will be preserved and can be copied to new accounts on the system. Additionally, user data can probably be restored from Time Machine backups or other backup solution.

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