Impossible to downgrade Mac Pro's operating system to original system
121309
How to downgrade from El Capitan to Snow Leopard?
69028
Can I downgrade to macOS Mojave if I buy the new 2019 MacBook Pro?
31948
Roll back from OS X Mavericks ( or any newer OS) to Mountain Lion
158908
How to completely disable auto-save and versions in Mac OS X Lion?
141667
Is Windows 10 OEM Home upgrade to Pro possible?
52382
Where can I get a copy of Mavericks after Yosimite has been released?
52087
How to re-download Lion from Mountain Lion
126915
Upgrading an old mac mini intel 1.1 for Lion
41495
How do I completely remove Ubuntu 12.04 on my Mac?
21236
How can I delete everything from my MacBook Pro before selling it?
150010
Installing Mavericks on a brand new machine that shipped with Yosemite pre-installed?
79327
How do you perform a clean install of macOS High Sierra with APFS?
89166
How to downgrade Kernel
135981
How do I reinstall macOS to my Mac after formatting the main drive accidentally?
33540
How can I switch a 32-bit installation to a 64-bit one?
3612
Can I downgrade to Mavericks after installing Yosemite (beta/developer preview)?
85706
How to set my default shell on Mac?