How To Mac

How to Fix macOS application is damaged, and can’t be used to install

Written by John

Hey there! Welcome back, today we will be talking about how to fix the error message “Application is damaged, can’t be used to install macOS”. This is an error message that pops up when you are trying to update or install a macOS. I don’t know about you but one of the most exciting things for me as a Mac user is updating my operating system to the most recent version of the macOS. It gives you a sense of expectation of what apple has to offer in the new OS. Research has shown that most people updated to the latest macOS or installed the latest macOS within 48 hours of its release.

Why the error message “This copy of the install macOS Application is damaged, can't be used to install macOS"?
The main reason you are getting the error message is that you are making use of old installers. In simpler terms, the error is because the macOS installation certificate expired on October 24, 2019. This bug appears on all versions from High Sierra, Mojave, and Catalina.

Can it be fixed?
Yes! There are two ways to fix it:
1. Change the date in the Terminal before the expiry date.
2. Download a new macOS installer.
In this article, you will learn how to fix the error in the 2 different ways.

Option 1: Install from a macOS Installer Image

I believe this is one of the most viable ways to update your macOS with no hassle. It is easier especially if you have a friend that has already downloaded the macOS. It saves you download time and installation time. All you need to do is just boot your Mac from the USB drive.

Enough beating around the bush, installing or updating macOS can be gruesome and frustrating especially if you are getting error messages. One of the most popular errors you can get during the process of installing macOS is "This copy of the install macOS Application is damaged, can't be used to install macOS".

Changing the date in the terminal before the expiry date:
This is unarguably the easiest way to resolve the "This copy of the Install macOS .app application is damaged, and can't be used to install macOS." All you need to do has been broken down into the following steps:

  • Disconnect internet before turning on your Mac, boot your Mac with Installer. Go to OS X Utilities screen, select Utilities and Terminal.
Open Terminal in macOS Utilities

  • Change the time in the Terminal with the command: date [mm] [dd] HH] MM [yy])
Change Date and Time inTerminal

From Yosemite and El Capitan: date 010101012015
From Sierra, High Sierra to Mojave, Catalina: date 010101012018

Press "Enter" the date command in the terminal and return to the OS X installer screen to continue the installation.

Option 2: Upgrade to new macOS Catalina

To be honest, this is the most preferred and safest way to install and update your mac. Downloading the installer directly from app store will not only ensure that the installer is the most recent one, but Apple will also make sure the certificate that comes with the installer has not expired. This can be done with the following steps;

  • Download the new version for macOS Catalina. This can be done by checking the app store for updates (for macOS High Sierra and earlier) or checking system preferences for updates (for macOS Mojave or later).
  • Check the time on your macOS. A wrong date on your macOS can cause serious installation problems for you. If the date and time is not right, you can change it by using Terminal with the date command. You can use this format: date [mm] [dd] HH] MM [yy]. For example, type “date 020310102019”.
  • Try reinstalling the macOS.

If you followed the above steps, you should not get any error messages during the installation process.

Updating and installing a macOS can be quite a challenge and frustrating especially if you keep receiving error messages like “This copy of the install macOS Application is damaged, can't be used to install macOS". Most often than not, the “damage” in the macOS is caused by an expired Installer certificate. As earlier said, you can either change the date to an earlier date (prior to the expiry date) or install the macOS directly from apple. Changing the date in the terminal is an easy and fast way while installing directly from apple is the safe and most preferred way.

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Deb Berkson
Deb Berkson
October 22, 2020 9:48 pm

Thank you from me too – I work at a school district and ran into this issue with all the different MacOS versions I tried. The Date-Change-Trick was the magic I needed and I am sure I will run into this again at some point…

Elisa Gonzalez
Elisa Gonzalez
September 7, 2020 7:36 pm

Thank you!

June 3, 2020 8:29 pm

Thanks so much for this. Need to have High Sierra on my early 2011 macpro for an online exam and was really struggling with the installation and the date fix saved me having to by a new mac when mine does everything I need.

April 2, 2020 6:58 am

Work perfectly with me after exploring almost everything. Many thanks

March 19, 2020 12:33 pm

I am not able to use my keyboard in the VM. It works fine on other VMs but it’s not working with MacOS and due to that I am not able to do the terminal thing. Is there any fix? I will be grateful if you could help me out in this.

March 19, 2020 5:39 pm
Reply to  Puneet

got it nvm

Graham Carter
Graham Carter
February 27, 2020 6:32 pm

Beautiful! As the other comments,needed to install Mojave and was unable to until stumbling across this article! Thank you!

February 18, 2020 7:12 pm

Brilliant ! Never realised support expiry would cause an installation to fail but your reasoning and approach was sound. Fixed my issue after hours of trying to re download and try 3 different USB sticks.

February 9, 2020 6:02 pm

Hi, it would be nice to share date settings for snow leopard to Mavericks also