Q: OSX App Store Not Installing Updates

From the Store menu, select

          Check for Unfinished Downloads...

This procedure will delete certain temporary and cache files used by system processes. The files are automatically generated and don't contain any of your data. Occasionally they can become corrupt and cause problems such as yours.

Back up all data and read this whole message before doing anything.

Triple-click anywhere in the line below on this page to select it:

/var/folders/zz

Right-click or control-click the highlighted line and select

          Services ▹ Reveal in Finder (or just Reveal)

from the contextual menu.* A folder should open with a subfolder named "zz" selected. Move that subfolder to the Trash. You may be prompted for your administrator login password. Restart the computer and empty the Trash.

IMPORTANT: It's been reported a few times that a computer failed to restart after the zz folder was moved to the Trash. If that happens, it means that the operating system is corrupt (and was already corrupt before you moved the folder.) In that case, there's no need to panic. Just reinstall the OS. If the system was upgraded from an older version of OS X, you may need the Apple ID and password you used. If you installed the Java runtime distributed by Apple and still need it, you'll have to reinstall it. The same goes for Xcode. All other data, including all your documents and settings, will be preserved.

*If you don't see the contextual menu item, copy the selected text to the Clipboard by pressing the key combination  command-C. In the Finder, select

          Go ▹ Go to Folder...

from the menu bar and paste into the box that opens by pressing command-V. You won't see what you pasted because a line break is included. Press return.

Hello Linc Davis,

Have done as per your post above, yet the trash is refusing to empty (please see screen shots). Have tried restarting, logging out...etc still the same message.

And still the App Store is not updating... (please see screen shots).

After pressing update, it stays like this for a few seconds and then...

moves back to this

It is worth mentioning that my iMAC (21" Mid 2013) started normally after removing the ZZ files.

Thank you in advance for your cooperation.

If you're running El Capitan, followed the instructions I posted above, and now can't empty the Trash, take either Step 1 or Step 2 below (not both.)

Step 1

Restore from the backup you made before moving the folder to the Trash. If you backed up with Time Machine, follow these instructions.

Step 2

This procedure will temporarily disable System Integrity Protection, a security feature of OS X that is preventing the Trash from being emptied. After you empty the Trash, the feature will be re-enabled. Nothing else will be changed.

Start up in Recovery mode. In the OS X Utilities screen, select Get Help Online. A copy of Safari will launch. While in Recovery, you'll have no access to your history or bookmarks, but you won't need them. Load this web page.

Triple-click anywhere in the line below to select it:

csrutil disable

Copy the selected text to the Clipboard by pressing the key combination command-C.

Quit Safari. You'll be returned to the OS X Utilities screen.

Select

          Utilities ▹ Terminal

from the menu bar. A Terminal window will open. Paste into the window by pressing the key combination command-V.

Wait for a new line ending in a dollar sign ($) to appear below what you entered. If it doesn't appear, press return.

Quit Terminal to return to the main screen.

Restart as usual. You should now be able to empty the Trash. As soon as you've done that, start up in Recovery mode again and load this page in Safari. Run the following command in Terminal as before:

csrutil enable

Restart as usual again.

Thank you so much, Linc Davis!  Your solution of deleting the "var > folders > zz" folder fixed my problem with the App Store not downloading or installing software updates.  I know I shouldn't have allowed such a relatively minor problem to frustrate and annoy me as much as it did, but it really was driving me nuts.  So thank you once again for the help.

I hope you don't mind, but I quoted and linked to your solution in another thread, where another person is having a similar problem with the App Store.

I also could not delete the folder so I renamed it zz old and placed it back in it's original location.

Hello, It is now March 2016 and I had this problem trying to update the El Capital Recovery 1.0 update from the App Store on my iMac. I would click on update and it would calculate for a bit, but the Update button would return. Instead of trying to delete zz files and whatnot I decided to ->

1. Restart my computer and try again....nothing so then I decided to ->

2. Run diagnostics by restarting holding down the D button, choosing my language and hitting return....It said "No Issues Found" and I wrote down the ref #

(You may have other issues so do this first and write down the ref# in case you need to contact support about it).

3. I contacted Apple support and they told me to Restart in Safe mode by restarting and holding down the left Shift key until I see the apple logo and then let go. It looks super weird when you do that but don't fret and when you see your screen normal again go to the App Store again and try to update.

This worked for me! It updated and then I restarted my computer again and now I am writing this in hopes it helps you. Cheers!