How To Fix “Application Is Damaged, Can’t Be Used To Install MacOS” Failure on older Macs

I hope this post will solve the issue if you run into it.

If you trying to install macOS High Sierra / El Capitan on an older like 2010 / 2011 or older. You get the Failure-message mentioned above and if you try to create an macOS-USB-Stick and run the installation from it the message is like “MacOS could not be installed on your computer”.

Solution 1:

Please check the following, did you redowload the macOS App? So the certificate issue is solved.

If so you should download the macOS App onto a current Mac Model fresh from AppStore and create a macOS-USB-Stick from the newer Mac, this should solve your issue with the AppStore Authentication, so you will be able to run the installation on your older Mac.