Recently, I received many messages from macOS users, informing that many users faced an error “Install MacOS Application is Damaged, Can’t be Used to Install MacOS” when reinstalling macOS Sierra 10.12, High Sierra 10.13 or macos Mojave 10.14. This error occurs because the Apple certificate for the installer just expired on October 24, 2019.
However, handling this error is not difficult. If you are facing the same trouble when reinstalling the macOS system, this guide will show you an instruction to fix the “install MacOS application is damaged, can’t be used to install MacOS” error on Mac computers
How to Fix “Install MacOS Application is Damaged, Can’t be Used to Install MacOS” Error
Once you have created a bootable USB flash drive to install macOS again on your computer, hold down the Option key ,then choose to boot from USB on the screen. After that, select Utilities > Terminal. Type in the command below in Terminal window:
Doing so will adjust the date and time of your Mac to return to January 1, 2018, 01:00. At this time, the Apple certificate is still valid. Depending on the macOS installer, you can change the date through command line in the format [mm] [dd][yy]. The command line currently works for both High Sierra and Mojave version. MacOS Catalina does not appear this error.
101610102014 <= Yosemite 10.10
123012122015 <= ElCapitan 10.11
121401582018 <= Sierra 10.12
102510102019 <= High Sierra 10.13
102510102019 <= Mojave 10.14
Once done, quit the Terminal and proceed reinstalling your macOS as usuall.