Ubiquity installer crashed during extra packages installation

[emi]

While installing Kubuntu 16.04 via a boot server (PXE/TFTP, DHCP, NFS).

ProblemType: Bug
DistroRelease: Ubuntu 16.04
Package: ubiquity 2.21.63.3
ProcVersionSignature: Ubuntu 4.4.0-41.61-generic 4.4.21
Uname: Linux 4.4.0-41-generic x86_64
ApportVersion: 2.20.1-0ubuntu2.1
Architecture: amd64
CasperVersion: 1.376
Date: Thu Oct 6 14:11:07 2016
InstallCmdLine: boot=casper netboot=nfs nfsroot=192.168.0.203:/srv/nfs/ubuntu/16.04-desktop-amd64 initrd=ubuntu/16.04-desktop-amd64/initrd.lz quiet splash console-setup/ask_detect=false console-setup/layoutcode=es debian-installer/locale=ca_ES maybe-ubiquity bootkbd=es -- bootkbd=es BOOT_IMAGE=ubuntu/16.04-desktop-amd64/vmlinuz.efi
LiveMediaBuild: Kubuntu 16.04.1 LTS "Xenial Xerus" - Beta amd64 (20161005)
ProcEnviron:
 LANGUAGE=
 TERM=xterm
 PATH=(custom, no user)
 LANG=ca_ES.UTF-8
 SHELL=/bin/bash
SourcePackage: ubiquity
UpgradeStatus: No upgrade log present (probably fresh install)