There have been reports of Aperture quitting after an update via the Mac App Store, and it turns out that Apple posted a KB (Knowledge Base) article about it a few days ago.
In a nutshell, if you are quitting on launch, then just throw away the Aperture app itself (not your Library!), and re-download from the App Store.
Here are the complete instructions, as posted at support.apple.com/kb/TS4471. Let us know in the comments if this is something you’ve run into, and if this helps!
After updating to Aperture 3.4.2 via the Mac App Store, Aperture may quit when you open it.
To resolve the issue, follow these steps to reinstall Aperture:
- In the Finder, choose Applications from the Go menu.
- Move the Aperture application to the Trash. Note: This will not remove or affect any of your photos or Aperture libraries.
- Open the App Store. Make sure you are logged in with the same Apple ID you used to purchase Aperture. If not, choose Sign In from the Store menu.
- Click the Purchases button at the top of the App Store window.
- In the list of your purchased apps, click the Install button to the right of Aperture. Note: If you don’t see Aperture listed you may have hidden it. See Mac App Store: Hiding and unhiding purchases for more information.