farewell to OS X, welcome to macOS

Thank you, kindly. With all the posts of problems with the process, I thought I would share one success story.

Discovered that my old version of Garage Band would not launch, so I installed the latest version which is working fine now. Had a few other .app updates to make, but so far things are running smoothly. Glad that the trusty ol' 2010 iMacs can run the newest macOS. With 16GB RAM and 1TB SSD drive, this machine still screams. Unfortunately, the video card is not up to date enough to run some of the latest games out there (Epic Games Fortnite is not supported, for example). But Inkscape and GIMP work fine on it as well as most of the tools I use on a daily basis.

One more thing that needed an update: my version 4 of Carbon Copy Cloner would no longer work in High Sierra, so I had to upgrade to version 5, they offered a discount at least. I still have my El Capitan clone on the USB drive, but I think if all goes smoothly at it has, I will eventually use that as my backup clone for High Sierra.

Well, one minor mishap for me just occurred in High Sierra. Not sure what the deal was, but I have seen other similar threads to my situation after other folks try a .point OS update. I will summarize my experience here. (2010 27" iMac was 10.13.3)

After trying to install the 10.13.4 update from AppStore I could not get the thing to reboot normally, a console log opens up with not much helpful info. I was able to boot into Safe Mode (shift key during startup) I found the 10.13.4 Combo Update from the Apple web site and downloaded that. I did have my external 10.11 hard drive also, where I was able to boot (by holding option to get startup disc manager) and run First Aid on the internal drive, no errors were found.

So, in my situation, after the failure of the AppStore 10.13.4 updater, I booted into Safe Mode (shift key) downloaded the 10.13.4 Combo Update and applied that. This takes a little longer and goes through a few reboots with beeps and chimes, and finally I am booted into 10.13.4. Have not shut down and restarted yet...

The lesson from this is: I should have cloned my new 10.13 drive to the external BEFORE applying a .point update...

at least I still have that 10.11 drive. I was amazed at how much longer it takes to boot from an external RPM-spinning drive as compared to the internal SATA-SSD drive.

So, my other 2010 iMac was able to apply the 10.13.4 update from AppStore just fine. Not sure why one of them had a glitch and required the Combo Update to be applied, but one installation was a success. Both are up and running now.