Fix is Damaged

A lot of Mac users have reported that they are not able to open some applications that they got from the Mac App Store. Whenever such an app is opened, an error comes up saying : is damaged and can’t be opened. Delete and download it again from the App Store.

Image : Mac App is Damaged Issues Fix is damaged

The error also has a variation, which comes up as a pop-up window and asks you to Sign in to use this application on this computer, for which you need to fill in your Apple ID and password.

Do not panic as this isn’t a major issue. These error messages come up because a code signing security certificate might have expired. It isn’t the fault of the user and generally denotes that something went wrong with the DRM at the Mac App Store. Nevertheless, the error message can be easily gotten rid of.

Fix App is damaged and can’t be opened Error in Mac :

Newer OS X versions are more prone to this error message.

  1. Firstly, reboot your Mac and see if the error message goes away.
  2. In case the application still gives out the error message, delete that app and then re-download it from Mac App Store.
  3. Now launch the app again and the error should be gone now.

Fix  Sign in to use this Application on this Computer :

apple id sign in

Older OS X versions are more likely to encounter this error message.

  1. When the Sign in to use this application error comes up, just close that dialog box and reboot your Mac.
  2. After rebooting, launch the Mac App Store and re-authenticate your Mac and its related apps by logging in with your Apple ID.
  3. Now launch the apps normally.

The sign in dialog box should not appear now.

Killing a Mac Process to Fix Errors :

fix mac damaged app issue

The storeaccountd processes can be targeted through the via Activity Monitor. In case you are familiar with the Terminal, you can also use the command line.

sudo killall -v storeaccountd

Typically, OS X runs two storeaccountd processes, one as root and one as user. So the killall command is enough to fix the issue.

If you are curious and want to learn more about the technicality behind the above-mentioned error messages, then you can check out this Twitter thread [ext link].




  1. same here I cant open it up there’s a problem with the starting proses where it just says “validating libraries” and nothing after that…

  2. I tried opening it on both my windows and mac. On my windows it says “Validating Libraries” then closes, and on my Mac it says that there’s an error. Please fix it as soon as possible cause I really need to downgrade from iOS 10.0.1 to iOS 9.3.3 or iOS 9.1

  3. I have a similar problem like Ziad. Older versions of Tinyumbrella should be made available for download for both iMac and MS Windows series i.e., XP or higher for compatability reasons. That way if a newer version doesn’t work on your OS, an older version may work. Hal

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