Packer vsphere template creation failing for Ubuntu 20.x


I am trying to build a template of Ubuntu 20.x using autoinstall. During autoinstall its prompting for autoinstall(yes / no). I have used Boot_command also as part of the configuration but still its stuck at autoinstall (Yes | No) window…

“boot_command”: [
"/casper/vmlinuz ",
"root=/dev/sr0 ",
"initrd=/casper/initrd ",
"autoinstall ",
Above is my configuration setting, but its still failing.