Grub error at boot on Ubuntu 20.04 ZFS install (Zsys)

[Sidh RTHA]

On last system upgrade I dropped on a Grub prompt .

After hours spent on internet from my smartphone, I managed to boot on my zroot fs with the following procedure :

NOTE : the following errors have been OCR-ized from pictures taken with smartphone, and most typos have been fixed (please forgive me for those remaining)

```
grub> set root=(hd1.gpt3)
grub> linux /BOOT/ubuntu.p8Ss19/@/vmlinuz root=ZFS=rpool/ROOT/ubuntu.p85s19 boot=zfs
grub> initrd /BOOT/ubuntu.p85s19/@/initrd.img
grub> boot
```

I don't know if it's related , but errors start appearing while installing new packages :

```
Processing triggers for man-db (2.9.1-1) ...
ZSys is adding automatic system snapshot to GRUB menu
Error Service took too long to respond. Disconnecting client
```

I would like to fix this boot error and any attempts I made with grub commands failed to this previous prompt.

Thank you for any hint or track you could provide.

Regards,

### error when install kernel update

```
image: initrd.img-5.11.0-25-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_twfvik
Found linux image: vmlinuz-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_41opy3
Found initrd image: initrd. ing-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_41opy3
Found linux image: vmlinuz-5.11.6-27-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_41opy3
Found initrd image: initrd.tmg-5.11.8-27-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_41opy3
Found linux image: vmlinuz-5.11.0-34-generic in rpool/ROOT/ubuntu p85sl9@autozsys_plzjig
Found initrd image: initrd.ing-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_plzjig
Found linux tmage: vnltnuz-5.11.0-27-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_plzjig
Found initrd image: initrd.img-5.11.0-27-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_plzjig
Found Linux image: vmlinuz-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_sug732
Found initrd image: initrd.ing-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_sug732
Found linux image: vmlinuz-5.11.0-27-generic in rpool/ROOT/ubuntu_p85sl9@autozsys sug732
Found initrd image: initrd.tmg-5.11.8-27-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_sug732
Found 11inux image: vmlinuz-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_pxcfk1
Found initrd image: initrd.ing-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_pxcfk1
Found linux image: vmlinuz-5.11.0-27-generic in rpool/ROOT/ubuntu_p85s19@autozsys_pxcfk1
Found initrd image: initrd.ing-5.11.0-27-generic in rpool/ROOT/ubuntu_p85s19@autozsys_pxcfk1
Found linux image: vmlinuz-5.11.0-34-generic in rpool/ROOT/ubuntu p85sl9@autozsys_b2d7pt
Found initrd image: initrd.img-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_b2d7pt
Found linux image: vmlinuz-5.11.0-27-generic in rpool/ROOT/ubuntu_p85s19@autozsys_b2d7pt
Found initrd image: initrd.ing-5.11.0-27-generic in rpool/ROOT/ubuntu_p85s19@autozsys_b2d7pt
Found linux image: vmlinuz-5.11.0-34-generic in rpool/ROOT/ubuntu_p85s19@autozsys_erboow
Found initrd image: initrd. tmg-5.11.8-34-generic in rpool/ROOT/ubuntu p85sl9@autozsys_erboow
Found linux image: vmlinuz-5.11.0-27-generic in rpool/ROOT/ubuntu p85sl9@autozsys_erbobw
Found initrd image: initrd.img-5.11.8-27-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_erbouw
Found linux image: vmlinuz-5.11.0-34-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_e8gz7y
Found initrd image: initrd.img-5.11.0-34-generic in rpool/ROOT/ubuntu_p85s19@autozsys_e8gz7y
Found Linux image: vmlinuz-5.11.0-27-generic in rpool/ROOT/ubuntu_p85sl9@autozsys_e8gz7y
Found initrd image: initrd.img-5.11.8-27-generic in rpool/ROOT/ubuntu_p85s19@autozsys_e8gz7y
/etc/grub.d/10_linux_zfs: 404: .: Can't open /tmp/zfsmat.TCEG2z/etc/os-release
device-mapper: reload ioctl on osprober-Linux-nvmeinip4 failed: Device or resource busy
Command failed.

Adding boot menu entry for UEFI Firmware Settings

done

root@ubuntu:/
```

### OS Version and dataset info

```
sidh@rochefort:~$ uname -a
Linux rochefort 5.11.0-34-generic #36~20.04.1-Ubuntu SMP Fri Aug 27 08:06:32 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux
sidh@rochefort:~$ lsb_release -rd
Description: Ubuntu 20.04.3 LTS
Release: 20.04
sidh@rochefort:~$ zfs list
NAME USED AVAIL REFER MOUNTPOINT
bpool 366M 1,39G 96K /boot
bpool/BOOT 364M 1,39G 96K none
bpool/BOOT/ubuntu_p85sl9 364M 1,39G 194M /boot
rpool 301G 590G 96K /
rpool/ROOT 16,3G 590G 96K none
rpool/ROOT/ubuntu_p85sl9 16,3G 590G 6,81G /
rpool/ROOT/ubuntu_p85sl9/srv 96K 590G 96K /srv
rpool/ROOT/ubuntu_p85sl9/usr 72,5M 590G 96K /usr
rpool/ROOT/ubuntu_p85sl9/usr/local 72,4M 590G 25,8M /usr/local
rpool/ROOT/ubuntu_p85sl9/var 6,31G 590G 96K /var
rpool/ROOT/ubuntu_p85sl9/var/games 96K 590G 96K /var/games
rpool/ROOT/ubuntu_p85sl9/var/lib 4,52G 590G 3,20G /var/lib
rpool/ROOT/ubuntu_p85sl9/var/lib/AccountsService 316K 590G 108K /var/lib/AccountsService
rpool/ROOT/ubuntu_p85sl9/var/lib/NetworkManager 2,21M 590G 268K /var/lib/NetworkManager
rpool/ROOT/ubuntu_p85sl9/var/lib/apt 172M 590G 81,3M /var/lib/apt
rpool/ROOT/ubuntu_p85sl9/var/lib/dpkg 165M 590G 55,5M /var/lib/dpkg
rpool/ROOT/ubuntu_p85sl9/var/log 1,78G 590G 1,37G /var/log
rpool/ROOT/ubuntu_p85sl9/var/mail 96K 590G 96K /var/mail
rpool/ROOT/ubuntu_p85sl9/var/snap 6,84M 590G 3,15M /var/snap
rpool/ROOT/ubuntu_p85sl9/var/spool 1,71M 590G 356K /var/spool
rpool/ROOT/ubuntu_p85sl9/var/www 96K 590G 96K /var/www
rpool/USERDATA 284G 590G 96K /
rpool/USERDATA/root_4qnsyq 596K 590G 168K /root
rpool/USERDATA/sidh_4qnsyq 284G 590G 109G /home/sidh
rpool/USERDATA/sidh_4qnsyq/vbox 114G 590G 96K /home/sidh/vbox
rpool/USERDATA/sidh_4qnsyq/vbox/fbsd113VM1 11,5G 599G 2,80G -
rpool/USERDATA/sidh_4qnsyq/vbox/fbsd113VM2 13,2G 601G 2,64G -
rpool/USERDATA/sidh_4qnsyq/vbox/fbsd113nfs 11,7G 600G 1,66G -
rpool/USERDATA/sidh_4qnsyq/vbox/win11 77,3G 649G 19,2G -
```

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

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[Sidh RTHA (s1dh)]

according to what I can see in the error message I provided, it is in the grub update process (during kernel updates) that the error occured.