I'm stuck on upgrading from Mojave to Catalina. (Yes, I'm late to the party.)
My most recent Time Machine backups continue to be from my Mojave system on an HFS+ Mac OS Extended (Journaled) filesystem. I'm trying to move my Mojave system to a new APFS drive so that I can install Catalina. When I do a full restore from my Time Machine backup onto my new hard drive, formatted as APFS, Time Machine changes the file system type to HFS+, which prevents me from upgrading to Catalina.
How do I get unstuck?
I have been running Mojave on an HFS+ filesystem. My original SSD hard drive was not S.M.A.R.T. enough and initial attempts at a Catalina failed with that error. It took a while, but I finally got a new SSD S.M.A.R.T. hard drive, used CCC to copy my existing system onto it, and installed it in my MacBook Pro (Yay!). I was now happily running Mojave on a new drive that was twice as big as my old one. Time to upgrade to Catalina!
Unfortunately, I thought the S.M.A.R.T. issue was all that I had to deal with, so I had naively formatted the new drive as HFS+, as I've been doing with Mac drives for a decade. When I attempted to upgrade to Catalina again, this time it complained about not having an APFS file system. (Feh!)
SO I booted from the old drive in an external case and reformatted the new drive as APFS. (Oops! There was some stuff that wasn't being backed up by Time Machine that I should have saved elsewhere. Oh well...)
I then did a full Time Machine restoration onto the new drive, now with its APFS file system. (I HATE being without my system for so many hours...)
It resulted in the previous multiple days of effort being wasted because the restoration reverted the filesystem back to HFS+! (And of course the Catalina installer won't tell me that until after it has spent some hours downloading the installation files.)
I know that I cannot be in some rare minority of people who somehow ended up with Mojave on HFS+ when they wanted to upgrade to Catalina. Yet I haven't found the questions and answers about how to get around the seeming Catch-22.
Is keeping Time Machine from reformatting the drive the right question?