How to Get your 'Damaged' Mac Apps Working Again

If you're seeing "damaged" apps on your Mac, you're not alone. A huge digital rights management blunder in Apple's Mac App Store on Wednesday, November 11th has rendered some apps unusable. When opening certain apps, the following message could be displayed:

• "[App Name]" is damaged and can't be opened. Delete "[App Name]" and download it again from the App Store.

The issue was caused by an out-of-date security certificate that expired on November 11th. These certificates are issued by Apple to make sure that you're running legit software on your computer, and to prevent malware from being run. The system can no longer validate certain application packages, so the apps appear broken.