14.04: Installer crashed with "An attempt to configure apt to install additional packages from the CD failed."

[Kakurady Drakenar]

I ran the installer from a downloaded Ubuntu 14.04 release image, written to a USB disk, to upgrade Ubuntu 13.10 to 14.04.
I've set the language as Chinese (Simplified), 'download updates during install' and 'install these extra packages' were checked, and when prompted what to do with Ubuntu 13.10 I chose to update.
But after completing all the pages in the installer, it exited with a warning message.

when I re-ran the installer in English, it said I already have Ubuntu 14.04 installed. After re-packing installed packages (which took a long time) it failed again, and I couldn't close the "Installer crashed" window.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: ubiquity 2.18.7
ProcVersionSignature: Ubuntu 3.13.0-24.46-generic 3.13.9
Uname: Linux 3.13.0-24-generic x86_64
ApportVersion: 2.14.1-0ubuntu3
Architecture: amd64
CasperVersion: 1.340
Date: Fri Apr 18 08:24:35 2014
InstallCmdLine: noprompt cdrom-detect/try-usb=true persistent file=/cdrom/preseed/ubuntu.seed boot=casper initrd=/casper/initrd.lz quiet splash -- locale=zh_CN keyboard-configuration/layoutcode?=cn
LiveMediaBuild: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcEnviron:
 PATH=(custom, no user)
 LANG=zh_CN.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.