I am trying to reinstall High Sierra on my late 2012 iMac after going to Catalina...
I am trying to reinstall High Sierra on my late 2012 iMac after going to Catalina... I was able to get back on Sierra from a time machine backup but now when I try to install high Sierra I get the "this copy is of macOS is damaged and cannot be used message. I have tried downloading a new version using App Store with no luck. Internet suggests it is an expired certificate.
iMac 21.5″, macOS 10.15