Dear Maintainer,
sudo apt-upgrade hangs when it is running grub-install and the grub
partition is on a removable disk.
I have Debian derivate Q4OS installed on a 128GB USB stick and
EndlessOS (another Debian derivate with read only root filesystem)
installed on the main disk. apt-upgrade hangs when it installs a new
kernel during grub-install. Using pstree -p for finding that process
and killing it after a
manual sudo grub-install --target-x86_64-efi --removable
in a separate window lets apt upgrade finish
Further information may be found in the Q4OS forum at
https://www.q4os.org/forum/viewtopic.php?id=4325