In previous versions of macOS you could show the installer log during system installation with the keyboard shortcut ⌘L. Since macOS Sierra, much of the system installation process happens on a black screen with a white Apple logo and a progress bar.
On that screen, you can use the keyboard shortcut ⇧⌃⌥⌘W, and it will switch back to traditional UI with the grey window. There you can then use ⌘L to show the log window again.
(Double mouse pointers are because I was running the installer in a VM to record the screen.)
Thanks much! Really informative about what the heck is going on during the deceptive and inaccurate progress bar that moves at a snails pace.
Wow! Awesome trick! Do you know if it also works with Mojave by any chance?
(a) the easiest to find that out is to just try yourself
(b) yes
(c) more here: https://www.youtube.com/watch?v=_TK_Y-PtEFI
This seems to have stopped working in later versions of Catalina’s installer (around 10.15.5 or so), and does not work with Big Sur’s installer. Did Apple remap the key combinations?
Yes, this has stopped working in some version of Catalina. You can still open a Terminal window with shift-ctrl-option-command T.