I chose "do something else" and set up an ext4 partition, and a 8gb swap partition, but it throws an error installing grub :-(

[Jared Meadows]

while installing ubuntu, for my partitions, I selected "Something else", and I set up a 8gb swap partition, and the remainder as a ext4 partition. I'm doing all this on my sdb hard drive, as well as setting up grub on sdb. however, I get this error when the installer is installing grub. :-(

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

Thank you for your help! :)

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: ubiquity 18.04.14.6
ProcVersionSignature: Ubuntu 4.15.0-29.31-generic 4.15.18
Uname: Linux 4.15.0-29-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.2
Architecture: amd64
CasperVersion: 1.394
Date: Sat Aug 4 12:51:28 2018
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash ---
LiveMediaBuild: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: grub-installer
UpgradeStatus: No upgrade log present (probably fresh install)

[Phillip Susi (psusi)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. This particular bug has already been reported and is a duplicate of bug 1766945, so it is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.