Bsrgvty

I try to install the minimal desktop from Ubuntu 18.04 with netboot and preseed.cfg. I have added the following line into preseed.cfg: ubiquity ubiquity/minimal_install boolean true, but it doesn't install the minimal installation, it still install the full version. The netboot image amd64 - For 64-bit Intel/AMD (x86_64) is downloaded from this url: http://cdimage.ubuntu.com/netboot/18.04/

All other settings from the file seem to work fine. The full preseed.cfg file:

d-i debconf/priority string critical
d-i auto-install/enable boolean true

# use -proposed udebs
d-i apt-setup/proposed boolean false

# minimal install (the only one not working!)
ubiquity ubiquity/minimal_install boolean true

# update and install packages
tasksel tasksel/first multiselect ubuntu-desktop
d-i pkgsel/update-policy select unattended-upgrades
d-i pkgsel/include string net-tools git ssh make mc openvpn xdotool wmctrl chrome-gnome-shell libxss1 libappindicator1 libindicator7 vino
d-i pkgsel/exclude string firefox update-manager avahi-daemon gnome-control-center gnome-software
d-i pkgsel/upgrade select full-upgrade

# localization
d-i debian-installer/language string en
d-i debian-installer/country string US
d-i debian-installer/locale string en_US.UTF-8

# keyboard
d-i console-setup/ask_detect boolean false
d-i keyboard-configuration/xkb-keymap select us

# use dhcp network configuration
d-i netcfg/choose_interface select auto
d-i netcfg/get_hostname string unassigned-hostname
d-i netcfg/get_domain string unassigned-domain

# user setup
d-i passwd/user-fullname string em-admin
d-i passwd/username string acc_admin
d-i passwd/user-password-crypted password [pass_here]

d-i user-setup/encrypt-home boolean false

# enable shadow passwords
d-i passwd/shadow boolean true

# hw clock
d-i clock-setup/utc boolean true
# time zone
d-i time/zone string Europe/Amsterdam

# release to install
d-i mirror/suite string bionic

# do not enable live installer, use normal instead
d-i live-installer/enable boolean false

# activate DASD, dasdfmt if needed
d-i s390-dasd/dasd string 0.0.0200,0.0.0300,0.0.0400

# DASD configuration
d-i s390-dasd/auto-format boolean true
d-i s390-dasd/force-format boolean true

# auto-partition, all files in one partition
d-i partman-auto/method string regular
d-i partman-auto/choose_recipe select atomic
d-i partman/choose_partition select finish
d-i partman/confirm_nooverwrite boolean true
d-i partman/confirm boolean true

# reboot at the end
d-i finish-install/reboot_in_progress note

The preseed.cfg still contains the line

tasksel tasksel/first multiselect ubuntu-desktop

which will install a full Ubuntu desktop system (tasksel). Remove the line and try again.