Bug 435473

SUMMARY

Error message:

Preparing to unpack .../grub-theme-breeze_5.21.4-0xneon+20.04+focal+release+build24_amd64.deb ...
Unpacking grub-theme-breeze (5.21.4-0xneon+20.04+focal+release+build24) over (5.21.3-0xneon+20.04+focal+build23) ...
dpkg: error processing archive /var/cache/apt/archives/grub-theme-breeze_5.21.4-0xneon+20.04+focal+release+build24_amd64.deb (--unpack):
 unable to make backup link of './boot/grub/themes/breeze/progress_bar2_c.png' before installing new version: Operation not permitted
dpkg-deb: error: paste subprocess was killed by signal (Broken pipe)
Errors were encountered while processing:
 /var/cache/apt/archives/grub-theme-breeze_5.21.4-0xneon+20.04+focal+release+build24_amd64.deb
ZSys is adding automatic system snapshot to GRUB menu
E: Sub-process /usr/bin/dpkg returned an error code (1)


STEPS TO REPRODUCE
1. Have KDE neon on ZFS filesystem with grub-theme-breeze in a version older than 5.21.4
2. apt update && apt dist-upgrade


OBSERVED RESULT

Package fails to install.


EXPECTED RESULT

Package can be installed without error.


SOFTWARE/OS VERSIONS
Windows: 
macOS: 
Linux/KDE Plasma: KDE Neon 5.21 User Edition
KDE Plasma Version: 5.21.4
KDE Frameworks Version: 5.80.0
Qt Version: 5.15.2

ADDITIONAL INFORMATION

It's possible to manually copy the images from an extracted package to the target folder, but installing the package fails.
Likely also related to this: https://bugs.launchpad.net/ubuntu/+source/lubuntu-artwork/+bug/1873008

Related entries from /etc/fstab:

# /boot/efi was on /dev/nvme0n1p3 during installation
UUID=(some uuid)  /boot/efi       vfat    umask=0022,fmask=0022,dmask=0022      0       1
/boot/efi/grub  /boot/grub      none    defaults,bind   0