Hello,
currently instance built with openSUSE-15.5 and 15.6 images provided on GCP
have below errors in Serial console logs:

[0m[37m[40merror: ../../grub-core/script/function.c:119:can't find command
`None'.
error: ../../grub-core/commands/terminal.c:113:terminal `serial' isn't found.
error: ../../grub-core/commands/terminal.c:113:terminal `serial' isn't found.
[0m[30m[40m[2J[01;01H[0m[37m[40m[02;30HGNU GRUB  version 2.06


Although instance is able to boot without any issue, but a customer reached out
asking why its happening. 

Is this expected behaviour for openSuse-leap-15.5 instance ? 

=================================================

Kernel version: 5.14.21-150500.55.62-default

opensuse-leap-15-5:~ # cat /etc/os-release
NAME="openSUSE Leap"
VERSION="15.5"
ID="opensuse-leap"
ID_LIKE="suse opensuse"
VERSION_ID="15.5"
PRETTY_NAME="openSUSE Leap 15.5"
ANSI_COLOR="0;32"
CPE_NAME="cpe:/o:opensuse:leap:15.5"
BUG_REPORT_URL="https://bugs.opensuse.org"
HOME_URL="https://www.opensuse.org/"
DOCUMENTATION_URL="https://en.opensuse.org/Portal:Leap"
LOGO="distributor-logo-Leap"
opensuse-leap-15-5:~ # 



opensuse-leap-15-5:~ # cat /etc/default/grub
# If you change this file, run 'grub2-mkconfig -o /boot/grub2/grub.cfg'
afterwards to update
# /boot/grub2/grub.cfg.

# Uncomment to set your own custom distributor. If you leave it unset or empty,
the default
# policy is to determine the value from /etc/os-release
# GRUB_DISTRIBUTOR=""

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=1
GRUB_CMDLINE_LINUX_DEFAULT="console=ttyS0,38400n8 net.ifnames=0 dis_ucode_ldr
multipath=off"
GRUB_CMDLINE_LINUX="root=LABEL=ROOT"

# Uncomment to automatically save last booted menu entry in GRUB2 environment
# variable `saved_entry'
#GRUB_SAVEDEFAULT="true"

# Uncomment to enable BadRAM filtering, modify to suit your needs
# This works with Linux (no patch required) and with any kernel that obtains
# the memory map information from GRUB (GNU Mach, kernel of FreeBSD ...)
#GRUB_BADRAM="0x01234567,0xfefefefe,0x89abcdef,0xefefefef"

# Uncomment to disable graphical terminal (grub-pc only)
#GRUB_TERMINAL=console

# The resolution used on graphical terminal
# note that you can use only modes which your graphic card supports via VBE
# you can see them in real GRUB with the command `vbeinfo'
#GRUB_GFXMODE=640x480

# Uncomment if you don't want GRUB to pass "root=UUID=xxx" parameter to Linux
#GRUB_DISABLE_LINUX_UUID=true

# Uncomment to disable generation of recovery mode menu entries
#GRUB_DISABLE_RECOVERY="true"

# Uncomment to get a beep at grub start
#GRUB_INIT_TUNE="480 440 1"
GRUB_DISABLE_LINUX_UUID=true
GRUB_DISTRIBUTOR="openSUSE-Leap-15.5"
GRUB_ENABLE_LINUX_LABEL=true
GRUB_GFXMODE=auto
#GRUB_SERIAL_COMMAND="None"
GRUB_TERMINAL_INPUT="console"
GRUB_TERMINAL_OUTPUT="console"
SUSE_REMOVE_LINUX_ROOT_PARAM=true

=================================================

I tested with one of the instance, and this can be fixed by changing options in
/etc/default/grub from

GRUB_SERIAL_COMMAND="None"
GRUB_TERMINAL_INPUT="serial"
GRUB_TERMINAL_OUTPUT="serial" 

to 

#GRUB_SERIAL_COMMAND="None"
GRUB_TERMINAL_INPUT="console"
GRUB_TERMINAL_OUTPUT="console"


Can someone please confirm if this is a bug and if we can permanently fix this
in image.