How to downgrade MACOS like Majove
1. Download majove DMG
https://apps.apple.com/cn/app/macos-sierra/id11127487414?mt = 12
2. make the boot disk
2.1 official way, Download the dmg of Majove
macappstores://apps.apple.com/app/macos-mojave/id1398502828?mt=12
or
https://support.apple.com/zh-cn/HT201372
b. Change the name of the Udisk to MyVolume
c. sudo /Applications/Install\ macOS\ Mojave.app/Contents/Resources/createinstallmedia –volume /Volumes/MyVolume
2.2 or Use Balenacher to make the boot disk, Do not use he windows to make the boot disk!
3. If you can’t use the U disk downgrade the system, then reboot, use option+control+shift+R, and power on. install the default online MACOS (Seems Apple closed the the below way to downgrade the factory system)
Then go to 2.1, and use the official way to make the Udisk downgrade again.
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