
Similar issues have happened with various Mac OS installers in the past. Let us know if that approach worked for you in the comments, or if you simply re-downloaded the installer from the Mac App Store.

If that fails, delete the installer and re-dowload it from Apple Now open the installer for MacOS Mojave again, it will run Enter your administer password to confirm. Click on the folder named “SharedSupport”. Right click on the installer and click “Show Package Contents”. Find the Installer for macOS Mojave in Applications folder You can also fix the This copy of the Install macOS Mojave.app application is damaged, and can’t be used to install macOS. This other approach to resolving the “Install MacOS Application is Damaged, Can’t be Used to Install MacOS” error message was left by reader Howard in the comments, and some users have had success with this too: Method 2: Modifying the Application Installer to Fix “Install MacOS Application is Damaged” Errors pkg components of the MacOS Installer with tools like Suspicious Package and pkgutil, which can show the expired certificate that causes the error message: If you want to see specifics and the expired certificate itself, you can investigate. “This copy of the Install macOS Sierra.app application is damaged, and can’t be used to install macOS.” “This copy of the Install macOS High Sierra.app application is damaged, and can’t be used to install macOS.”

“This copy of the Install macOS Mojave.app application is damaged, and can’t be used to install macOS.” If you do not download new versions of these macOS installer applications, you are likely to encounter the error messages for each release if you attempt to open or use the MacOS installer, or even a USB boot drive created with one of the expired installers: You may need to reboot the Mac after you have downloaded the new (and valid certificate) installer application, particularly if you had already launched a version that showed the application damaged error message.

The easiest way to resolve the “This copy of the Install macOS. Resolving “Install MacOS Application is Damaged, Can’t be Used to Install MacOS” Error Messages with Mac OS System Installers Fortunately, there is a fairly simple solution to the “damaged” installer problem. The cause of this error is an expired certificate, and because the certificate is expired the “Install macOS” app for Mojave, Sierra, and High Sierra will not run.
