Error “unknown filesystem” in GRUB, no matter what I do
https://askubuntu.com/questions/1566355/error-unknown-filesystem-in-grub-no-matter-what-i-doTwo days ago I ran “apt upgrade” on a Ubuntu 24.04 machine to get a kernel update, and as usual a reboot was suggested. However, the machine (in a data center far away) did not come back up, and using a remote console I found out that GRUB seems to have some kind of issue:
<- this is supposed to be an inline image: https://imgur.com/a/X6vrel0
GNU GRUB version 2.12
Minimal BASH-like line editing is supported. For the first word, TAB
lists possible command completions. Anywhere else TAB lists possible
device or file completions. To enable less(1)-like paging, "set
pager=1". ESC exits at any time.
grub> set pager=1
grub> lsmod
error: unknown filesystem
grub> ls
error: unknown filesystem
grub> lspci
error: unknown filesystem
grub> _
How did an “apt upgrade” get my GRUB into a state where it cannot even perform an “ls?” And more important, how do I get GRUB out of that state?
(This question clearly differs from Grub rescue - error: unknown filesystem, in that whatever is going on in this question can obviously not be solved by running “ls” because, as shown above, only an error message is displayed, as reaction to many basic GRUB commands, except set, insmod, and recordfail. I’ve tried recreating the steps that grub.cfg lists for the default “Ubuntu” menu entry, but everything that’s not an insmod gets met with “error: unknown filesystem”. I’m not sure how to proceed from here.)



