Everyone knows that Apple signs the firmware of its mobile system for the iPhone and iPad. But few people know what turns out to be, she signs the macOS desktop system, and if you want to install a version that is no longer signed, you will receive a message with approximately the following content:

“Application is damaged, can’t be used to install macOS”

Here some ways for fix this trouble.

Fix Installation macOS Errors

In this case, you have two solutions:

  • download the latest image of the desired system from the Mac App Store and recreate the bootable USB flash drive;
  • change the date of your Mac to the one that preceded the release of the build with macOS(OS X).

If the first method requires more time and effort from you, then the second can be done directly in the installer mode without restarting the Mac.

Read more: What is “Copy Error Code 0” Means in macOS?

Fix macOS Installation Errors with Terminal

All that will be needed is to launch the Terminal program and use it to change the date. Change the date a few days before the update is released so that it works. macOS release dates can be viewed on the Wikipedia website.

How to use the Terminal to change the date in the macOS installer:

  • In the menu bar, click “Utilities” and select Terminal;
  • You can view the set date using the command:
date
  • In order to change it, you need to add the date to the date command in the format: mmddHHMMyy
date mmddHHMMyy

mm – month (01-12);

dd – date (01-31);

HH – hours (00-23);

MM – minutes (00-59);

yy – year.

For example, 20:31 on January 9, 2014 will look like this: date 0109203102014

Conclusion

This is not really a panacea, but when I came across a similar problem it helped me reinstall macOS Sierra. After the steps have been taken, you will no longer have an error and you can safely install macOS. You can download and install the latest updates already in the system itself.

Will this method work with macOS Mojave or macOS Catalina? If you succeed to do this on the latest systems, please report this in the comments.

Author

Hi there! My Name is Vincent Lago! My goal is to share insightful reviews, guides, and manuals for people looking to know more about current solutions for Apple hardware and OS. I have years of technological background knowledge including owning a custom iMacs & PCs which was using for different types of business. And now, I want to share my experience with you.

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