[SOLVED] GRUB Error 22 or "Attempt to read or write outside 'hd0'" after recent update

[Silent Observer]

I'm running 22.04.3 on the HWE kernel path on an AMD Fx8350 with 32 GB RAM and nVidia GTX1040.

After receiving updates to the 5.15.x (skipped restart, since I'm not using that kernel) and this morning to the 5.6.0.*, my system won't even boot to GRUB -- I've seen Error 22 or a more verbose (but still not helpful, to me) "Attempt to read or write outside 'hd0'" followed by landing in Rescue Mode -- in which I haven't a clue what to do next.

I presume I'll now need to boot from a 22.04 USB stick (got one somewhere, or I can make a fresh one on my laptop), but what to do after that isn't at all obvious. If it matters (and it might) I had run grub-customizer some time ago and though I no longer need or want it, it seems less than trivial to restore GRUB to its Ubuntu-standard state (i.e. automatically boots to latest kernel, with links in /boot maintained by kernel update installer).

Help! Please!

[Schwarzer Kater]

5.6.0.* - is this the kernel version that you are using in Kubuntu 22.04 ?!?

[Silent Observer]

Woops. Couldn't see it since the computer wouldn't even start into GRUB -- and that wouldn't affect GRUB starting up, I wouldn't think. In fact, it's 6.2.0.*, I think. Whatever the HWE stack is running on.

[Silent Observer]

The same update worked fine on my laptop (different hardware, of course -- Core i5 (2 cores/4 threads, 3.9 GHz), 16 GB RAM, Intel graphics (Thinkpad T430). And it is 6.2.0-39-generic, replacing 6.2.0-36-generic. Again, I don't think it's the kernel itself that's causing the problem, it's something that went wrong updating GRUB.

I have a thumb drive with boot-repair, but the last time I ran that I had to reinstall my entire system...

[Schwarzer Kater]

I would probably look in the direction of the Nvidia drivers for something to blame (-> prejudices…).
And did you check the integrity of the drive itself or the file system? It could also be a hard- or software issue concerning the drive. That you can do e.g. from a bootable USB stick.

[Silent Observer]

Once again, it's hard to blame something in the OS for failure to even load GRUB.

Also, my system gets restarted often enough (due to kernel updates) that there are opportunities for fsck to do its thing as scheduled

In fact, once I had time to find some decent instructions on what options to select ("Recommended Repair" and nothing else) Boot Repair fixed it -- and removed the effects of grub-customizer that I've been wanting to get rid of for a while.