Re: grub2 user interface disappears after upgrade from stretch to testing

Shane Dev composed on 2018-11-12 22:25 (UTC+0100):

> Hello, I downloaded firmware-9.6.0-amd64-netinst.iso and successfully
> installed a minimal debian stretch on my UEFI/GPT disk. After rebooting, I
> was presented with the grub2 text user interface and the possibility to
> boot Debian or my Windows boot manager - as expected.

> Following https://wiki.debian.org/DebianTesting, I
> edited /etc/apt/sources.list and changed stretch to testing, apt update &&
> apt upgrade. Everything seemed ok but when I rebooted, the grub2 user
> interface was gone and I could not find a way to boot Debian. Any ideas?

By "gone", do you mean an entirely black screen? Or, do you see a few lines
of help text followed by a

	grub> _

prompt? If the latter you can type in, along with tab completion, the commands
to load "linux" and "initrd", just like a grub menu does for you, except you don't
actually need everything the defaults usually provide, as any of it is necessary
is included in the initrd. Those you need should be in your backup of grub.cfg.

If you're getting nothing, try using your BIOS boot selection menu, which may
have been poorly changed by the upgrade process to in inappropriate choice.
Without actually entering BIOS setup it could be F12, F8, F9 or a number of
other keystrokes that are firmware dependent.

If you can't find your grub.cfg backup, use the following from one of mine as
a template:

	load_video
	set gfxpayload=keep
	search --no-floppy --set=root --hint-baremetal=ahci0,gpt10 --label p10deb10
	linux	/boot/vmlinuz root=LABEL=p10deb10 noresume
	initrd	/boot/initrd