Q: Mac App Store does not open

Launch the Console application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad. Click Utilities, then Console in the icon grid.

Make sure the title of the Console window is All Messages. If it isn't, select All Messages from the SYSTEM LOG QUERIES menu on the left. If you don't see that menu, select

View ▹ Show Log List

from the menu bar.

Click the Clear Display icon in the toolbar. Then try the action that you're having trouble with again. Select any messages that appear in the Console window. Copy them to the Clipboard by pressing the key combination command-C. Paste into a reply to this message by pressing command-V.

When posting a log extract, be selective. In most cases, a few dozen lines are more than enough.

Please do not indiscriminately dump thousands of lines from the log into this discussion.

Important: Some private information, such as your name, may appear in the log. Anonymize before posting.

Please read this whole message before doing anything.

This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.

The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, by a font conflict, or by corruption of the file system or of certain system caches.

Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards, if applicable. Start up in safe mode and log in to the account with the problem. You must hold down the shift key twice: once when you turn on the computer, and again when you log in.

Back up all data.

Quit the App Store if it's running. Force quit if necessary.

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

defaults write -app "App Store" ShowDebugMenu YES

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

Launch the built-in Terminal application in any of the following ways:

☞ Enter the first few letters of its name into a Spotlight search. Select it in the results (it should be at the top.)

☞ In the Finder, select Go ▹ Utilities from the menu bar, or press the key combination shift-command-U. The application is in the folder that opens.

☞ Open LaunchPad. Click Utilities, then Terminal in the icon grid.

Paste into the Terminal window by pressing the key combination command-V. I've tested these instructions only with the Safari web browser. If you use another browser, you may have to press the return key after pasting.

Wait for a new line ending in a dollar sign ($) to appear below what you entered. You can then quit Terminal.

Launch the App Store. There should now be a menu labeled Debug in the menu bar at the top of the screen. From that menu, select

Reset Application

defaults delete -app "App Store" ShowDebugMenu

Read this whole message before doing anything.

Back up all data.

Quit the App Store application if it’s running.  Wait at least 10 seconds before continuing.

Step 1

Hold down the option key and select

Go ▹ Library

from the Finder menu bar. Delete the following items from the Library folder (some may not exist):

• Caches/com.apple.appstore
• Caches/com.apple.storeagent
• Caches/storeagent
• Containers/com.apple.appstore
• Cookies/com.apple.appstore.cookies
• Preferences/ByHost/com.apple.appstore.*.plist
• Preferences/ByHost/com.apple.storeagent.*.plist
• Preferences/com.apple.storeagent.plist

Here * stands for a long string of letters, numbers, and dashes. Leave the Library folder open. Try the App Store again. If it works now, stop here. Close the Library folder.

Step 2

If you still have problems, quit again and wait 10 seconds. Go back to the Finder and move the following item from the open Library folder to the Desktop:

Step 3

If you still have problems, quit the App Store again.

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

open $TMPDIR../C

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

Paste into the Terminal window as before. A folder should open. Inside that folder, there may be subfolders with the names

• com.apple.appstore
• com.apple.WebKit.WebContent+com.apple.appstore

If so, delete them. You can then quit Terminal. Test.

Please read this whole message before doing anything.
  
This procedure is a diagnostic test. It won’t solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.
   
The purpose of this test is to determine whether the problem is localized to your user account. Enable guest logins* and log in as Guest. Don't use the Safari-only “Guest User” login created by “Find My Mac.”
   
While logged in as Guest, you won’t have access to any of your personal files or settings. Applications will behave as if you were running them for the first time. Don’t be alarmed by this; it’s normal. If you need any passwords or other personal data in order to complete the test, memorize, print, or write them down before you begin.
   
Test while logged in as Guest. Same problem?
     
After testing, log out of the guest account and, in your own account, disable it if you wish. Any files you created in the guest account will be deleted automatically when you log out of it.
  
*Note: If you’ve activated “Find My Mac” or FileVault in OS X 10.7 or later, then you can’t enable the Guest account. The "Guest User" login created by "Find My Mac" is not the same. Create a new account in which to test, and delete it, including its home folder, after testing.

Launch iTunes and select from the menu bar

iTunes ▹ Preferences... ▹ Advanced

Click the buttons marked

Reset warnings

and

Reset cache

Log out or restart the computer. Test.