My 2cents of Advice for Upgrading Mac OS: Use APFS Advanced Features

I have seen many posts regarding troubles when upgrading Mac OS from Mojave
to later iterations such as Big Sur and Monterey.
For many, this advice is Monday-morning quarterbacking proverbially speaking …

One of the coolest things I (finally) discovered with Apple’s transition to APFS file system is the on-the-fly disk formatting capabilities.

When moving from High Sierra to later versions of Mac OS, I cleaned house and backed up the drive, and then formatted new Partitions, leaving the High Sierra volume alone, in which I could then clean install completely independent systems. One can also opt to simply add volumes (multiple containers) in which to install different Mac OS versions in order to test them out.

In choosing this method I think I have avoided some of the pitfalls of upgrading like problematic networking issues after a new system is installed over an existing one.
There are some cons to this in the need to reconfigure a lot of stuff on a new system, but to me seems preferable to having to troubleshoot anomalies arising from a new system upgrade flubbing up an already well-working one.

It’s definitely more work, of course if you need to keep Mac OS 10.12.Sierra, but even then it might be well worth the trouble to reformat a drive and re-install Sierra on a HFS+ partition, and add High Sierra or later on a separate partition in order to take advantage of APFS features

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I’ll just add, since it seems to be a hot topic today…Your screen will turn totally black during the update and would appear to be completely shut down. This is most likely not the case and you need to leave your Mac alone and not choose to hit the power button for any reason. Users have reported it taking an hour or so to complete what it’s doing and continue with the update, so resist the urge to take any action because you believe things are taking too long.


Precisely, Al! Patience is a virtue. I learned the hard way, while visiting a friend and upgrading my MacBook (when else do I get to use it but when away from home?), and I bailed on what appeared to be a failed upgrade. Fortunately, I had my external backup drive (which I’d backed up to, immediately prior to the upgrade), so I could boot from that, restore, and then do the OS upgrade again. I resolved in future not to be so impatient!