Xcode 5.1 won't launch -- "being updated" -- but already installed

xcode mac-appstore software-update

  1. Show the App Store's Debug menu (enter the following in Terminal):

    defaults write com.apple.appstore ShowDebugMenu -bool true

  2. Select Reset Application and restart the App Store

  3. Log in to the App Store through the Purchases tab.

  4. Reboot.

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