Installation fails with exit code 141 and a reference to /var/log/syslog
In /var/log/syslog it says:
Mar 24 11:04:31 kubuntu ubiquity: W: gpgv:/var/lib/apt/lists/Kubuntu%2016.04%20LTS%20%5fXenial%20Xerus%5f%20-%20Beta%20amd64%20(20160323)_dists_xenial_Release.gpg: The repository is insufficiently signed by key C5986B4F1257FFA86632CBA746181433FBB75451 (weak digest)
Complete file is attached.
ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.51
ProcVersionSignature: Ubuntu 4.4.0-15.31-generic 4.4.6
Uname: Linux 4.4.0-15-generic x86_64
ApportVersion: 2.20-0ubuntu3
Architecture: amd64
CasperVersion: 1.368
Date: Thu Mar 24 12:12:38 2016
ExecutablePath: /usr/lib/ubiquity/bin/ubiquity
InstallCmdLine: file=/cdrom/preseed/kubuntu.seed boot=casper maybe-ubiquity initrd=/casper/initrd.lz quiet splash ---
InterpreterPath: /usr/bin/python3.5
LiveMediaBuild: Kubuntu 16.04 LTS "Xenial Xerus" - Beta amd64 (20160323)
ProcEnviron:
PATH=(custom, no user)
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)
Looks like it's really the appstream update that failed:
Mar 24 11:04:30 kubuntu ubiquity: ** (appstreamcli:
Mar 24 11:04:30 kubuntu ubiquity: AppStream cache update failed.
The warning you saw earlier should be fixed in the next image; perhaps it would be best to see if the next daily solves the issue for you, and if not we'll look more into the appstream issues.
As far as I recall, appstream was pretty picking about the signing.