Hello everyone,
Since a simple update (as far as I remember: apt update + apt upgrade), I face off an issue regarding the booting of Ubuntu (20.04) on my laptop (Acer Aspire 5).

Problem: the boot of my Ubuntu is blocked with the error:
"Boot args (cat /proc/cmdline)
Missing modules (cat /proc/modules; ls /dev)
ALERT! UUID=[...] does not exist. Dropping a shell!

(initramfs) _"
And I am not able to locate the root partition and follow this answer (https://forums.linuxmint.com/viewtopic.php?t=47594)

Issues:
- 'blkid' shows nothing
- 'ls /dev/' shows no "sda*" or "hd*" directories...

If you have anything in mind regarding my problem, please let me know.
If it is not possible to solve (in the worst case), would it be possible for me to recover my data? (If so, how?)

Thanks a lot for reading me.

There's no busybox required to boot ubuntu, so I gather it's the busybox included in the initrd. If the boot goes belly up it drops you to a (busybox) shell, remember? If grub was dropping you to a shell, I'd expect it to be a little more organized about it. So it's busybox.

Anyhow, it's a mess. If your system attempted a kernel update, this sort of thing is unusual, not unknown. Now if you had a backup, you could just install it instead of posting here.

Now you're going to have to boot something to sort this. What have you got that boots? Let's start from there. Spare box? Install DVD? Live usb? You posted, so you probably have something.

Did you attempt to boot one of the older kernels in the grub sub-menu?