Unable to open some applications downloaded from the Mac App Store maybe an annoying moment you have as mac user. Sometimes when ypu try to open an impacted app in OS X, a message said “Name.app is damaged and can’t be opened. Delete Name.app and download it again from the App Store.” will be shown, or a window appearing asking a user to “Sign in to use this application on this computer” requesting an Apple ID and password.
The reason why these app can’t be opened and give uou error messages is because of a code signing security certificate has expired. It does not mean user error or anything to do with user involvement. Usually it happen because something with DRM that was messed up on the Mac App Store side that impacting a few applications that were downloaded from there. This is a strange , annoying and frustrating error message, but it’s really easy to fix.
Fixing the “App is damaged and can’t be opened” Error in OS X. This error message usually appear in new versions of OS X:
Reboot the Mac, this one action is just enough to fix the problematic apps and remove the error message
But if a reboot is not enough to fix the app, delete the application, then re-launch the Mac App Store and download it again via the Purchases tab or you can search for the app manually
Open the impacted apps again, it should be work fine now.
Fixinh the “Sign in to use this application on this computer” Error in OS X. This error message usually appear in older versions of OS X:
First, directly close the “sign in to use this application” error dialog box after you see it, after that reboot the Mac. After reboot, open the Mac App Store and log in to your Apple ID to re-authenticate the Mac and all related apps.
Open the apps as usual, That steps should fix your apps to work again in OS X.
The faster App Error Fix for proficient Mac Users: Killing a Process
If you wish you can target the storeaccountd processes via Activity Monitor, or if you are comfortable with the terminal you can use the command lind:
sudo killall -v storeaccountd
There are two “storeaccountd” processes running, one as user, and one as root, and by using killall on both is just enough to fix the issue.
Obviously if you never see these error messages on your Mac, you do not have to worry. But, at least if you see one someday, you know it’s not hard to fix and the apps aren’t actually damaged, it’s just an error on the Apple.