The ‘grub-efi-amd64-signed’ package failed to install into /target/. Without the GRUB boot loader, the installed system will not boot.

[BluePr1nt-X]

In Cubic's chroot environment,...

$ apt update $ apt upgrade $ apt install grub-efi-amd64-signed

Then Click Next.

This will make sure the latest version of "grub-efi-amd64-signed" is available for Ubiquity during installation, so it does not have to be downloaded.

(2) On the "Package Manifest" tab, search for "grub-efi-amd64-signed"

Under the "Typical" column, select the checkbox for this package.

This will remove "grub-efi-amd64-signed" from the final installed system, after Ubiquity finishes. (If you need to keep "grub-efi-amd64-signed" on your installed system, just make sure it is un-checked). https://answers.launchpad.net/cubic/+question/680446

[BluePr1nt-X]

Tested and resolved. Offline installation is now achievable.