I think I've seen that error message before after an install.
To fix it I did as it says in the note here: https://wiki.archlinux.org/title/EFI_system_partition#Mount_the_partition

Add a file in /etc/modules-load.d/vfat.conf

with contents:

vfat
nls_cp437
nls_ascii

Pretty sure that solved my issue, have you tried that?

I had not tried that, but it unfortunately did not solve my issue. When it tries to load that module early, the journal outputs the same:

systemd-modules-load¹⁹¹: Failed to insert module 'vfat': No such file or directory

Even when I am using the installation media and attempting to reconfigure grub, I get an "unknown file-system" error.

I am confused because I have not updated my kernel in the past couple weeks, which is when most people seem to have similar issues.

Commenting out this mount in /etc/fstab does allow my computer to boot into my usual environment, however, which is quite a help for the time being.

Well, you could try temporarily downgrading the kernel I suppose.

When you reconfigure grub, what command are you using?
By the way, I'm assuming you actually do have an EFI partition and that it is mounted when you try to reconfigure grub - otherwise I think it might fail.

Also, I suggest maybe running grub-install again, I remember I had to do that a while ago, something like this:

grub-install --target=x86_64-efi --efi-directory=/efi --bootloader-id=GRUB --removable --recheck /dev/sdaX

Obviously correct /efi and /dev/sdaX to your own paths.

I was running grub-install, but I do not think grub is the issue--the installation media is the only system capable of mounting my ESP. When I try to configure grub when I am arch-chrooted into my standard root directory, it complains it is unable to even read the filesystem. I do not think the update I did yesterday regenerated my initramfs files yesterday--so I am guessing one of the packages installed yesterday failed... I could try to look up what each one does, and reinstall whichever ones I suspect, though I am not sure if that would be successful.

It is strange to me that my pacman cache only contains .zst files for the package versions currently installed on my system. I have never had to downgrade packages, though I had thought it preserved a large history of versions:

pacman -Q feh
feh 3.10.1-2

ls -la /var/cache/pacman/pkg/*feh*
-rw-r--r-- 1 root root 189057 Oct 2 18:14 /var/cache/pacman/pkg/feh-3.10.1-2-x86_64.pkg.tar.zst
-rw-r--r-- 1 root root    566 Oct 2 18:14 /var/cache/pacman/pkg/feh-3.10.1-2-x86_64.pkg.tar.zst.sig

Is this expected?

Is what expected? That your cache only has the current version?
No I'd say that is not the default - do you have a hook that removes older versions?
Something like a /etc/pacman.d/hooks/paccache.hook file ?

Maybe there's an archived version somewhere on the net, or maybe you can try linux-libre-lts ?

Speaking of which have you tried checking /etc/mkinitcpio.conf ?
Maybe it was modified, I'm sure you've tried mkinitcpio -p linux-libre already.
Though that really shouldn't matter.
Maybe it actually is something with the new kernel version after all..

I think I am addressing the wrong issue now. I have noticed that my wireless, ethernet, and mousepad do not function in my environment, after skipping the problem with the vfat module. There are some new failures in my journal file when iwd.service and dhcpcd fail to start:

iwd[291]: No HMAC(SHA1) support found
iwd[291]: No HMAC(MD5) support found
iwd[291]: No CMAC(AES) support found
iwd[291]: No HMAC(SHA256) support found
iwd[291]: No HMAC(SHA512) support found, certain TLS connections might fail
iwd[291]: DES support not found
iwd[291]: AES support not found
iwd[291]: No CBD(DES3_EDE) support found, certain TLS connections might fail
...
iwd[291]: The following options are missing in the kernel:
iwd[291]:         CONFIG_CRYPTO_USER_API_HASH
iwd[291]:         CONFIG_CRYPTO_USER_API_SKCIPHER
iwd[291]:         CONFIG_CRYPTO_USER_API_ECB
iwd[291]:         CONFIG_CRYPTO_USER_API_MD5
iwd[291]:         CONFIG_CRYPTO_USER_API_CBC
iwd[291]:         CONFIG_CRYPTO_USER_API_SHA256
...

I do not know where to look for anything related to ethernet or the mousepad, however. I am not sure if this is the usual output for this kernel (likely not, because I use these services normally).

I also have no hook files in that directory. I have not had a problem with space--so I did not manually try to configure pacman to remove cached versions. I have only really configured my mirrorlist.

I am having this same issue after a system upgrade. The only packages that were upgraded for me were kmod and parabola keyring.

Could this have something to do with kmod? It's a dependency of linux-libre and it's description says "Linux kernel module management tools and library"

My last kernel upgrade was May 23 to 6.3.3-1. My fstab looks normal. UUID's and mountpoints are correct.

I am have the exact same issue as OP.

Did you fix this problem? If not, when did you install the update that broke your system?

You should try reverting those updates if you have the older versions still in your cache. I am unable to, but am curious if that would fix it.

Wow, thank you cshep, I overlooked that package. Reinstalling kmod 30-3 from the archlinux archive fixed this issue for me, at least until I need to re-update.

That makes sense, the next thing I was going to ask for was to grep for vfat in /lib/modules/6.x.y/*

And now I see there's actually an issue for kmod too, might want to confirm this then: https://labs.parabola.nu/issues/3539

You're right. I suppose I should check there sooner if I have another issue like this. Thank you for your help, Necklace