after a call to apple support, with them on the phone, we couldn’t get back into recovery, couldn’t run diagnostics, couldn’t do anything other than just login to a ‘slow’ machine, etc.
scheduled a genius bar appointment tomorrow morning…
hangup call…random brain fart moment…
-unplugged time machine hard drive from hub
-unplugged carbon copy cloner hard drive from hub
30 seconds later…
Disk Utility ran and was good - check
Reinstalled macOS through recovery - check
Everything seems to be fine and running normal.
But what is the root cause? failing hub? failing externals?
Nothing wrong with that. But… definitely not during a restore (and ideally not even during a OS update). USB devices can be everything. What they really are to the Mac depends on how they identify themselves. The Mac “learns” through drivers that are coming with a MacOS installation. As long as those are missing, the Mac has the problem not knowing what exactly is connected to the Mac. And this can lead to unexpected results. Even more so, if USB devices are connected through a hub, which makes stuff even more complicated.
I do not unplug every USB device during an update (who does…), but IF an error occurs, it is the first thing to be done before doing anything else.
EDIT: I have forgotten the most important thing: I am glad that everything is up and running again.