This question Error unknown command hwmatch is exactly what I'm asking but was closed as non reproducible. Mine is very reproducible.
Ubuntu 18.04 freshly installed on a 64-bit UEFI machine. Default grub boot options work fine, but I wanted to add a brief countdown (my normal config). After editing
/etc/default/grub as normal and running
sudo update-grub, the countdown works, but I get the error shown in the question title.
I tried the solution (copying files) in the closed question but it didn't seem to fit my configuration. Frankly I found the answer confusing.
I also tried editing
/etc/grub.d/10_linux to comment out the IF-THEN structure that uses
hwmatch. After that I did a
sudo update-grub but I still got the error.
How can I get my countdown and not see this error?
Edit per comments -
Stock grub as installed (all non-commented-out lines shown)
GRUB_DEFAULT=0 GRUB_TIMEOUT_STYLE=hidden GRUB_TIMEOUT=0 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX=""
Edited grub to give countdown (all non-commented-out lines shown)
GRUB_DEFAULT=0 GRUB_TIMEOUT_STYLE=countdown GRUB_TIMEOUT=5 GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian` GRUB_CMDLINE_LINUX_DEFAULT="quiet splash" GRUB_CMDLINE_LINUX=""