Hirsute snapd dep8 on s390x fails, and it's due to grub-common:
$ sudo apt-get -V install grub-common
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following additional packages will be installed:
libfreetype6 (2.10.4+dfsg-1)
os-prober (1.77ubuntu1)
Suggested packages:
multiboot-doc
xorriso (1.5.2-1)
desktop-base (10.0.3ubuntu1)
The following NEW packages will be installed:
grub-common (2.04-1ubuntu37) libfreetype6 (2.10.4+dfsg-1)
os-prober (1.77ubuntu1)
0 upgraded, 3 newly installed, 0 to remove and 280 not upgraded.
Need to get 2202 kB of archives.
After this operation, 15.3 MB of additional disk space will be used. Do you want to continue? [Y/n]
Get:1 http://us.ports.ubuntu.com/ubuntu-ports hirsute/main s390x libfreetype6 s390x 2.10.4+dfsg-1 [383 kB]
Get:2 http://us.ports.ubuntu.com/ubuntu-ports hirsute/main s390x grub-common s390x 2.04-1ubuntu37 [1804 kB]
Get:3 http://us.ports.ubuntu.com/ubuntu-ports hirsute/main s390x os-prober s390x 1.77ubuntu1 [14.9 kB]
Fetched 2202 kB in 0s (36.2 MB/s) [15/122]
Preconfiguring packages ...
Selecting previously unselected package libfreetype6:s390x.
(Reading database ... 54831 files and directories currently installed.)
Preparing to unpack .../libfreetype6_2.10.4+dfsg-1_s390x.deb ...
Unpacking libfreetype6:s390x (2.10.4+dfsg-1) ...
Selecting previously unselected package grub-common.
Preparing to unpack .../grub-common_2.04-1ubuntu37_s390x.deb ...
Unpacking grub-common (2.04-1ubuntu37) ...
Selecting previously unselected package os-prober.
Preparing to unpack .../os-prober_1.77ubuntu1_s390x.deb ...
Unpacking os-prober (1.77ubuntu1) ...
Setting up libfreetype6:s390x (2.10.4+dfsg-1) ...
Setting up grub-common (2.04-1ubuntu37) ...
Created symlink /etc/systemd/system/multi-user.target.wants/grub-common.service → /lib/systemd/system/grub-common.service.
Created symlink /etc/systemd/system/multi-user.target.wants/grub-initrd-fallback.service → /lib/systemd/system/grub-initrd-fallback.service.
Created symlink /etc/systemd/system/rescue.target.wants/grub-initrd-fallback.service → /lib/systemd/system/grub-initrd-fallback.service.
Created symlink /etc/systemd/system/emergency.target.wants/grub-initrd-fallback.service → /lib/systemd/system/grub-initrd-fallback.service.
Job for grub-initrd-fallback.service failed because the control process exited with error code.
See "systemctl status grub-initrd-fallback.service" and "journalctl -xe" for details.
update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
Job for grub-common.service failed because the control process exited with error code.
See "systemctl status grub-common.service" and "journalctl -xe" for details.
invoke-rc.d: initscript grub-common, action "start" failed.
● grub-common.service - Record successful boot for GRUB
Loaded: loaded (/lib/systemd/system/grub-common.service; enabled; vendor preset: enabled)
Active: failed (Result: exit-code) since Tue 2021-02-02 11:52:15 UTC; 6ms ago
Process: 1993 ExecStartPre=/bin/sh -c [ -s /boot/grub/grubenv ] || rm -f /boot/grub/grubenv; mkdir -p /boot/grub (code=exited, status=0/SUCCESS)
Process: 1996 ExecStart=/usr/bin/grub-editenv /boot/grub/grubenv unset recordfail (code=exited, status=1/FAILURE)
Process: 1997 ExecStartPost=/bin/sh -c if grub-editenv /boot/grub/grubenv list | grep -q initrdless_boot_fallback_triggered=1; then echo "grub: GRUB_FORCE_PARTUUID set, initrdless boot paniced, fallback triggered."; fi (code=exited, status=0/SUCCESS)
Main PID: 1996 (code=exited, status=1/FAILURE)
Feb 02 11:52:15 ppisati-s390x-m1-tiny-bos01-test2 systemd[1]: Starting Record successful boot for GRUB...
Feb 02 11:52:15 ppisati-s390x-m1-tiny-bos01-test2 grub-editenv[1996]: /usr/bin/grub-editenv: error: cannot rename the file /boot/grub/grubenv.new to /boot/grub/grubenv.
Feb 02 11:52:15 ppisati-s390x-m1-tiny-bos01-test2 systemd[1]: grub-common.service: Main process exited, code=exited, status=1/FAILURE
Feb 02 11:52:15 ppisati-s390x-m1-tiny-bos01-test2 systemd[1]: grub-common.service: Failed with result 'exit-code'.
Feb 02 11:52:15 ppisati-s390x-m1-tiny-bos01-test2 systemd[1]: Failed to start Record successful boot for GRUB.
dpkg: error processing package grub-common (--configure):
installed grub-common package post-installation script subprocess returned error exit status 1
dpkg: dependency problems prevent configuration of os-prober:
os-prober depends on grub-common; however:
Package grub-common is not configured yet.
dpkg: error processing package os-prober (--configure):
dependency problems - leaving unconfigured
Processing triggers for systemd (246.6-2ubuntu1) ...
No apport report written because the error message indicates its a followup error from a previous failure.
Processing triggers for man-db (2.9.3-2) ...
Processing triggers for libc-bin (2.32-0ubuntu3) ...
Errors were encountered while processing:
grub-common
os-prober
E: Sub-process /usr/bin/dpkg returned an error code (1)
grub is not used on s390x.
please do not install grub on s390x.