Furthermore, I looked for the postinst script and found out that it's just the « grub-install » command which fails.
root@ingatech-XPS-13-9343:~# LC_ALL=C grub-install Installing for x86_64-efi platform. Could not delete variable: Invalid argument grub-install: error: efibootmgr failed to register the boot entry: Block device required. The attached file is a dump of a grub-install -v Hope this helps... ** Attachment added: "grub-install -v" https://bugs.launchpad.net/ubuntu/+source/grub2-signed/+bug/1753518/+attachment/5070954/+files/grub-install.txt -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1753518 Title: package grub-efi-amd64-signed 1.93+2.02-2ubuntu8 failed to install/upgrade: installed grub-efi-amd64-signed package post- installation script subprocess returned error exit status 1 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2-signed/+bug/1753518/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
