Installation apt configuration problem

[Ian Grace]

I've been trying to install Ubuntu 18.04.1 64-bit on an apparently healthy Seagate (Model ST3320310CS) SATA HDD. Each time a dialog box tells me there is an apt configuration problem "An attempt to configure apt to install additional package from the CD failed". I am then told that the installation has failed. In the case of Ubuntu I've been using a USB key.

I've already tried installing Ubuntu Mate 18.04.1 on the same HDD on 2 different 64-bit computers (with both a USB key and DVD) and the message I received was very similar to the above.

Thanks in advance for any replies.

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: Fri Jan 4 00:39:23 2019
InstallCmdLine: BOOT_IMAGE=/casper/vmlinuz initrd=/casper/initrd.lz file=/cdrom/preseed/ubuntu.seed boot=casper quiet splash ---
LiveMediaBuild: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)