Packer not submitting full boot command

Currently running on a local machine with hyper-v Config is below, however Ive tried numerous boot commands in which Im only ever getting partial of the text through and it just hangs, unsure what the issue is in particularly here

source "hyperv-iso" "vm" {

  iso_checksum          = "F8449B103C9FE9A4A80004D19046A4220B25DFAA532825F9F86A4D6B42DFA7F4"
  iso_url               = "./debian-10.10.0-amd64-DVD-1.iso"
  vm_name               = "Debian2"
  headless              = "true"
  communicator          = "ssh"
  ssh_wait_timeout      = "1800s"
  ssh_password          = "vagrant"
  ssh_username          = "vagrant"
  enable_secure_boot    = "false"
  disk_block_size       = "1"
  disk_size             = "30000"
  cpus                  = "2"
  memory                = "4096"
  enable_dynamic_memory = "true"
  generation            = "1"
  guest_additions_mode  = "disable"
  switch_name           = "Ext"
  temp_path             = "."
  boot_wait             = "5s"
  http_directory= "http"
  boot_command = [
    "auto <wait>",
    " preseed/url=http://{{ .HTTPIP }}:{{ .HTTPPort }}/preseed.cfg <wait>",
  shutdown_command      = "echo 'vagrant' | sudo -S shutdown -P now"
  shutdown_timeout      = "30m"
build {
  sources = ["source.hyperv-iso.vm"]
  provisioner "shell" {
    inline            = ["sleep 30","sudo apt-get update && sudo apt-get upgrade -y"]



# Debian 10 (buster) preseed file - preseed-buster.cfg
# For more information on preseed syntax and commands, refer to:
# For testing, you can fire up a local http server temporary.
# Download the preseed.cfg file locally, cd to the directory where the
# preseed.cfg resides and run hte following command:
#  $ python -m SimpleHTTPServer
# You don't have to restart the server every time you make changes.  Python
# will reload the file from disk every time there is a request.  As long as you
# save your changes they will be reflected in the next HTTP download.  Then to
# test with a PXE boot server, use the following kernel boot parameters:
#  > linux auto url=http://<your_ip>:8000/preseed.cfg hostname=<hostname> locale=en_US keyboard-configuration/modelcode=SKIP
# NOTE: If you netboot/PXE boot Debian, it will ignore the value in hostname,
# but you must provide a hostname as a boot parameter to prevent the Debian
# install from prompting for a hostname

# Account setup
d-i passwd/root-login boolean false
d-i passwd/user-fullname string Vagrant User
d-i passwd/username string vagrant
d-i passwd/user-password-crypted password c35daf02fe116c1c978aac3316d4f047f3d0d4610923c5cd1769a51f527320ad9df2615164305fea6d41bf8e22023a6e537d248aa3f920fce931b542a954a9d5
d-i user-setup/encrypt-home boolean false
d-i user-setup/allow-password-weak boolean true
# Clock and time zone setup
d-i clock-setup/utc boolean true
d-i time/zone string UTC
d-i clock-setup/ntp boolean true
# Partitioning
d-i partman-auto/method string lvm
d-i partman-lvm/device_remove_lvm boolean true
d-i partman-md/device_remove_md boolean true
d-i partman-lvm/confirm boolean true
d-i partman-lvm/confirm_nooverwrite boolean true
d-i partman/choose_partition select finish
d-i partman-auto-lvm/guided_size string max
d-i partman-auto/choose_recipe select atomic
d-i partman/default_filesystem string ext4
d-i partman/confirm_write_new_label boolean true
d-i partman/confirm boolean true
d-i partman/confirm_nooverwrite boolean true
# Scan another CD or DVD?
apt-cdrom-setup apt-setup/cdrom/set-first boolean false
# Package mirror
d-i mirror/country string manual
d-i mirror/http/hostname string
d-i mirror/http/directory string /debian
d-i mirror/http/proxy string
d-i apt-setup/use_mirror boolean true
# Don't send reports back to the project
popularity-contest popularity-contest/participate boolean false
# Package selection
tasksel tasksel/first multiselect standard
# Automatically install grub to the MBR
d-i grub-installer/only_debian boolean true
d-i grub-installer/bootdev string default
# Turn off last message about the install being complete
d-i finish-install/reboot_in_progress note
d-i pkgsel/include string openssh-server ntp curl nfs-common linux-headers-$(uname -r) build-essential perl dkms net-tools
# This first command is run as early as possible, just after
# preseeding is read.
# Prevent packaged version of VirtualBox Guest Additions being installed:
d-i preseed/early_command string sed -i \
  '/in-target/idiscover(){/sbin/discover|grep -v VirtualBox;}' \

Screenshot 2022-05-17 234344

Include your packer version.

Increase your boot_wait … 5s maybe too fast.

Hi Thanks for your response, Im currently on the latest “Packer v1.8.0”

as for the boot time I put it at 30 seconds trying the following boot commands

  boot_command = [
    "auto <wait>",
    " preseed/url=http://{{ .HTTPIP }}:{{ .HTTPPort }}/preseed.cfg <wait>",


        "install <wait>",
        " preseed/url=http://{{ .HTTPIP }}:{{ .HTTPPort }}/preseed.cfg <wait>",
        "debian-installer=en_US.UTF-8 <wait>",
        "auto <wait>",
        "locale=en_US.UTF-8 <wait>",
        "kbd-chooser/method=us <wait>",
        "keyboard-configuration/xkb-keymap=us <wait>",
        "netcfg/get_hostname={{ .Name }} <wait>",
        "netcfg/ <wait>",
        "fb=false <wait>",
        "debconf/frontend=noninteractive <wait>",
        "console-setup/ask_detect=false <wait>",
        "console-keymaps-at/keymap=us <wait>",
        "grub-installer/bootdev=/dev/sda <wait>",

unsure where Ive gotton both now as the debian example in the docs seems to be checking for audio drivers