How downgrade macOS to previous versions safely?
4309
How can I download an older version of OS X/macOS?
59814
macOS High Sierra: Where is the Secure Empty Trash option?
101714
Is there any way to roll back the most recent upgrade?
29500
Can I undo the upgrade to iOS 7 by restoring to iOS 6.1.3?
7580
How to safely upgrade from an older Ubuntu version to a newer one?
151232
downgrading rails 4 to 3.2
98421
How will people upgrade from 12.10 to later releases after 13.04 is EOL?
106321
Finding out if upgrading to a newer macOS version will cause issues?
112347
How much of 32-bit support is dropped in macOS Catalina?
47002
How do I downgrade to Subversion 1.6?
31948
Roll back from OS X Mavericks ( or any newer OS) to Mountain Lion
135547
Downgrading from OS X 10.9.2 to 10.9
105231
How to downgrade a package using dpkg
36529
How to revert an update?
97346
Is it possible to skip releases during an upgrade?
32200
How do I downgrade a package?
54472
How to reinstall macOS Sierra after formatting by Ubuntu