How to fix corrupted macOS installer errors
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How to fix corrupted macOS installer errors

Creating a bootable macOS installer on USB provides a convenient way to install a new copy of macOS on multiple Macs, while also allowing you to perform a “clean” installation quickly and easily.

If you’ve recently tried to run your installer and suddenly get a message saying it is corrupt and unusable, don’t worry! Keep reading the following simple way to fix the problem.

Why is the macOS installer broken?

Sometimes when using the macOS installer, you may get an error message that says something like:

This copy of the Install macOS application is damaged, and can’t be used to install macOS.

(This copy of the Install macOS application is corrupt and cannot be used to install Mac operating systems).

Error installing installer message
Error installing installer message

As Apple explained in a newly published support document, the likely cause of this “broken installer” error message is that the certificate expires. Fortunately, the repair is very simple.

How to fix a corrupted macOS installer

To fix a corrupted installer, simply reload the installer. Doing so will also ensure that you have all macOS updates that have been released since you created the original installer, meaning you won’t have to update macOS as soon as the initial installation is completed.

You can find the latest official download links below for the 4 most recent versions of Apple’s Mac operating system, all with new unexpired certificates:

  • macOS Catalina
  • macOS Sierra
  • OS X El Capitan
  • OS X Yosemite

To learn how to perform a clean “macOS” installation using a bootable USB method, please refer to the following articles:

  • How to perform a clean install of macOS 10.15 Catalina
  • Instructions on how to install (clean install) macOS Sierra 10.12 on Mac
  • Create a bootable copy of the OS X Mountain Lion installer


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