Grub rescue says all partitions have 'Filesystem is unknown'

Question

I have simple Windows 10 and Ubuntu installation. My latest Windows update just messed with my GRUB boot loader somehow.

Every other answer mentions to type a few

set boot

and

set prefix

However every time I get 'Filesystem is unknown', for every of the 4 partitions inside my hd0.

Any clues?

Solution

As Greg Gómez states, a Live Ubuntu USB will allow you to download and install Boot Repair. Often, this GUI utility can remedy boot issues, so I've made a persistent boot USB with Boot Repair preinstalled for use after each Windows update mangles booting. N.B. Use the fastest flash USB drive you have for persistence, since the drive is accessed frequently (as opposed to an ordinary Live USB, in which much is moved to RAM).

If nothing else fixes the issue, make an image of the drive, reinstall Ubuntu using the existing partition, then copy back the ext4 Ubuntu partition.

Comments

[Daniel Santos]

I understand your point however I cannot reinstall the whole system. I simply need to fix the MBR. My questions is how to approach this fix through GRUB Rescue only (no Windows recovery disk or Ubuntu recovery disk).

[Daniel Santos]

I understand your point however I cannot reinstall the whole system. I simply need to fix the MBR. My questions is how to approach this fix through GRUB Rescue only (no Windows recovery disk or Ubuntu recovery disk).

[Daniel Santos]

I am marking this a solution even if it was not what a looked for. Since I could not wait, I decided to move forward entering linux into live mode and I simply repaired GRUB inside the linux installation through GRUB repair.

[DrMoishe Pippik]

@DanielSantos, well done... I'm glad grub repair worked. Since it's handy to have that and Boot Repair, I've made a Live Ubuntu with persistence and installed those to the USB drive.