backup disk formatting

[Dan Lester]

OK, let me wrap things up here. Dave and I did some discussion offline, but he finally suggested just dumping my High Sierra and reloading it. That took some effort as the Apple instructions for recovery were poor, and loads of people have had problems with the "The recovery server could not be contacted" error and the 2000F error in the reinstall package which were a big waste of time. But I finally just went to the App Store, downloaded the OS and over-installed it that way. Bottom line is that now everything works GREAT. I can now back up to an APFS drive, and boot from it, which for some bizarre reason I was unable to do before. Problem solved. So my OS just got corrupted in some subtle way. Thanks to Dave for his sage advice.