not sure, may be High Sierra too.Īnd don't forget, you can always install macOS which was shipped with your Mac from the Internet. It is not available from Mojave, Catalina. Old installer is still available in Mac App Store. and ready to boot from new Sierra installer with new certificate. Copy new 'Install macOS Sierra.app' to the USB drive you created before (step 2.3)Ģ.7. Then use InstallOS.dmg (new installer) to install new 'Install macOS Sierra.app' in you Application folder. When you finish, delete 'Install macOS Sierra.app' from USB drive and from the trash bin at all! It's important! It looks like empty USB, but it is NOT!Ģ.5. Use old installer to create USB-installer according to this article: Ģ.4. Make backup of this two files (zip them all and save to another place).Ģ.3. You need the old install (because in new one the execution file of createinstallmedia is not works. If you want new USB installer for macOS with new certificate you need to do more steps:Ģ.1.

It will set the system date before the certificate expiration date.

Open Terminal from Utility menu and run this command: when you boot from usb-drive, don't click to install macOS. Use old one 'Install macOS Sierra.app', but!. To get bootable Sierra Installer you can:ġ.

Download mac os 10.12