Fix “App is Damaged Can’t Be Opened” Error Messages in Mac OS X
Some Mac users have discovered they are unable to open some applications downloaded from the Mac App Store. When attempting to open an impacted app in Mac OS, a message stating “Name.app is damaged and can’t be opened. Delete Name.app and download it again from the App Store.” Another variation is a pop-up window appearing asking a user to “Sign in to use this application on this computer” requesting an Apple ID and password.
The reason these app can’t be opened error messages are appearing may be because of a code signing security certificate expired, in which case this is not user error or anything to do with user involvement, it’s basically something with DRM that was messed up on the Mac App Store side but is now impacting some applications that were downloaded from there. Sometimes it can also be the result of a fluke issue when downloading an app from the App Store. Yes, this is a strange and frustrating error message, but it’s easily resolvable.
Resolving the “App is damaged and can’t be opened” Error in Mac OS X
This error message tends to appear in new versions of Mac OS X:
- Reboot the Mac, this alone may be sufficient to fix the problematic apps and remove the error message
- If a reboot does not fix the app, delete the application (just drag it to the Trash and empty), then re-launch the Mac App Store and download the app again via the Purchases tab or by searching for the app manually
- Open the once impacted apps again, they should now work fine
Method 2: Fixing “App is damaged and can’t be opened” Error on Mac App Launch
If the above approach does not work, you may need to include a few additional steps:
- Delete the app in question from the Mac
- Log out of the Mac App Store
- Restart the Mac
- Upon reboot, open the Mac App Store and log in to the App Store again
- Re-Download the app in question
This “App is damaged and can’t be opened” error message occasionally happens even in modern macOS releases like macOS Big Sur. Fortunately, deleting the app, rebooting, and re-downloading it again usually resolves the issue quickly.
Resolving the “Sign in to use this application on this computer” Error in Mac OS X
Another variation of this error message may appear in older versions of Mac OS X:
- Close the “sign in to use this application” error dialog box when you see it, and reboot the Mac instead
- Upon 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 should be all that is required to get your apps working again in OS X.
The Quick App Error Fix for Advanced Mac Users: Killing a Process
You can target the storeaccountd processes via Activity Monitor if you want, or use the command line if you are comfortable with the Terminal:
sudo killall -v storeaccountd
There are typically two “storeaccountd” processes running, one as user, and one as root, and thus using killall on both is sufficient to resolve the issue.
Those interested in learning a bit more about the technical details behind these error messages can refer to this Twitter thread, which reveals the certificate that expired and speculates on various contributing factors.
Well that would explain the MAS problem. pic.twitter.com/Nuqj9Uxxiz
— Paul Haddad (@tapbot_paul) November 12, 2015
Obviously if you haven’t seen these error messages on your Mac, you have nothing to worry about, and can go about your merry way. But, should you see them, at least know it’s a simple fix, the apps aren’t actually damaged, it was just an error on the Apple side of things with a quick remedy.
Note that you may sometimes see a similar but different error message stating the particular Mac “app is damaged and can’t be opened, you should move it to the Trash” which has a different potential set of solutions.