A measure of success! Instead of trying to boot from the NVMe drive, I updated the SATA SSD drive and set it up to boot EFI-stub. It booted right up, updated things, and generally settled into the new hardware with only minor problems. So far, then, it seems clear that I had at least two problems: (a) disabling Secure Boot, and (b) some undiagnosed problems about booting from the NVMe drive. While (a) might have been anticipated, (b) was a surprise, and I still don't know why the NVMe drive is problematic. But I can solve that problem later, with the help of all the suggestions and advice people have offered. Once I iron out the minor problems (no network), I'll then try booting from the NVMe drive via a bootloader -- rEFInd and GRUB2 have been proposed -- to see if that helps. But having a working system makes it much less urgent. Thanks again to one and all! -- Peter King peter.king@utoronto.ca Department of Philosophy 170 St. George Street #521 The University of Toronto (416)-946-3170 ofc Toronto, ON M5R 2M8 CANADA http://individual.utoronto.ca/pking/ ========================================================================= GPG keyID 0x7587EC42 (2B14 A355 46BC 2A16 D0BC 36F5 1FE6 D32A 7587 EC42) gpg --keyserver pgp.mit.edu --recv-keys 7587EC42