root@mint-System-Product-Name:/etc/grub.d# cat /etc/grub.d/15_custom
#!/bin/sh
exec tail -n +3 $0
menuentry "Linux Mint" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-245d8512-eee9-47a3-8dd9-17952920d509' {
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
linux /boot/vmlinuz root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro
initrd /boot/initrd.img
}
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
root@mint-System-Product-Name:/etc/grub.d#

root@mint-System-Product-Name:/etc/grub.d# sudo update-grub
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/50_linuxmint.cfg'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.19.0-41-generic
Found initrd image: /boot/initrd.img-5.19.0-41-generic
Found linux image: /boot/vmlinuz-5.15.0-71-generic
Found initrd image: /boot/initrd.img-5.15.0-71-generic
Found MX 19.4 patito feo (19.4 ) on /dev/sda1
Found Microsoft Windows XP Professional on /dev/sdc1
Found linux image: /boot/vmlinuz-5.19.0-41-generic
Found initrd image: /boot/initrd.img-5.19.0-41-generic
Found linux image: /boot/vmlinuz-5.15.0-71-generic
Found initrd image: /boot/initrd.img-5.15.0-71-generic
Found MX 19.4 patito feo (19.4 ) on /dev/sda1
Found Microsoft Windows XP Professional on /dev/sdc1
done
root@mint-System-Product-Name:/etc/grub.d#

Error still there after reboot

is it still the same error?
post the contents of /boot/grub/grub.cfg

mint@mint-System-Product-Name:~$ cat /boot/grub/grub.cfg
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
if [ "${initrdfail}" = 2 ]; then
set initrdfail=
elif [ "${initrdfail}" = 1 ]; then
set next_entry="${prev_entry}"
set prev_entry=
save_env prev_entry
if [ "${next_entry}" ]; then
set initrdfail=2
fi
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="MX 19.3 patito feo (19.3 ) (on /dev/sda1)"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function initrdfail {
if [ -n "${have_grubenv}" ]; then if [ -n "${partuuid}" ]; then
if [ -z "${initrdfail}" ]; then
set initrdfail=1
if [ -n "${boot_once}" ]; then
set prev_entry="${default}"
save_env prev_entry
fi
fi
save_env initrdfail
fi; fi
}
function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}

if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
set gfxmode=auto
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=en_US
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ] ; then
set timeout=30
else
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=hidden
set timeout=8
# Fallback hidden-timeout code in case the timeout_style feature is
# unavailable.
elif sleep --interruptible 8 ; then
set timeout=0
fi
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux_proxy ###

function gfxmode {
set gfxpayload="${1}"
if [ "${1}" = "keep" ]; then
set vt_handoff=vt.handoff=7
else
set vt_handoff=
fi
}
if [ "${recordfail}" != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if [ ${grub_platform} != pc ]; then
set linux_gfx_mode=keep
elif hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode



### END /etc/grub.d/10_linux_proxy ###

### BEGIN /etc/grub.d/30_os-prober_proxy ###
menuentry "MX Linux 19.4 patito feo (19.4 ) (on /dev/sda1)" --class mx --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-simple-6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro quiet splash
initrd /boot/initrd.img-4.19.0-14-amd64
}
### END /etc/grub.d/30_os-prober_proxy ###

### BEGIN /etc/grub.d/40_custom_proxy ###
menuentry "Linux Mint" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
linux /boot/vmlinuz-5.4.0-146-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro quiet splash $vt_handoff
initrd /boot/initrd.img-5.4.0-146-generic
}
### END /etc/grub.d/40_custom_proxy ###

### BEGIN /etc/grub.d/41_linux_proxy ###
submenu "Advanced options for Ubuntu"{
menuentry "Ubuntu, with Linux 5.19.0-41-generic" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.19.0-41-generic-advanced-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
echo 'Loading Linux 5.19.0-41-generic ...'
linux /boot/vmlinuz-5.19.0-41-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro quiet splash $vt_handoff
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.19.0-41-generic
}
menuentry "Ubuntu, with Linux 5.19.0-41-generic (recovery mode)" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.19.0-41-generic-recovery-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
echo 'Loading Linux 5.19.0-41-generic ...'
linux /boot/vmlinuz-5.19.0-41-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro recovery nomodeset dis_ucode_ldr
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.19.0-41-generic
}
menuentry "Ubuntu, with Linux 5.15.0-71-generic" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.15.0-71-generic-advanced-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
echo 'Loading Linux 5.15.0-71-generic ...'
linux /boot/vmlinuz-5.15.0-71-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro quiet splash $vt_handoff
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.15.0-71-generic
}
menuentry "Ubuntu, with Linux 5.15.0-71-generic (recovery mode)" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.15.0-71-generic-recovery-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
echo 'Loading Linux 5.15.0-71-generic ...'
linux /boot/vmlinuz-5.15.0-71-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro recovery nomodeset dis_ucode_ldr
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.15.0-71-generic
}
}
### END /etc/grub.d/41_linux_proxy ###

### BEGIN /etc/grub.d/42_linux_zfs ###
### END /etc/grub.d/42_linux_zfs ###

### BEGIN /etc/grub.d/43_linux_xen ###

### END /etc/grub.d/43_linux_xen ###

### BEGIN /etc/grub.d/44_os-prober_proxy ###
menuentry "Microsoft Windows XP Professional (on /dev/sdc1)" --class windows --class os $menuentry_id_option 'osprober-chain-1470355270353BB4' {
insmod part_msdos
insmod ntfs
set root='hd2,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd2,msdos1 --hint-efi=hd2,msdos1 --hint-baremetal=ahci2,msdos1 1470355270353BB4
else
search --no-floppy --fs-uuid --set=root 1470355270353BB4
fi
parttool ${root} hidden-
drivemap -s (hd0) ${root}
chainloader +1
}





set timeout_style=menu
if [ "${timeout}" = 0 ]; then
set timeout=10
fi
submenu "Advanced options for MX 19.4 patito feo (19.4 ) (on /dev/sda1)"{
menuentry "Debian GNU/Linux (on /dev/sda1)" --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-4.19.0-14-amd64--6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro quiet splash
initrd /boot/initrd.img-4.19.0-14-amd64
}
menuentry "Debian GNU/Linux, with Linux 4.19.0-14-amd64 (on /dev/sda1)" --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-4.19.0-14-amd64--6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro quiet splash
initrd /boot/initrd.img-4.19.0-14-amd64
}
menuentry "Debian GNU/Linux, with Linux 4.19.0-14-amd64 (systemd) (on /dev/sda1)" --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-4.19.0-14-amd64--6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro quiet splash init=/lib/systemd/systemd
initrd /boot/initrd.img-4.19.0-14-amd64
}
menuentry "Debian GNU/Linux, with Linux 4.19.0-14-amd64 (recovery mode) (on /dev/sda1)" --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-4.19.0-14-amd64-root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro single-6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro single
initrd /boot/initrd.img-4.19.0-14-amd64
}
}
### END /etc/grub.d/44_os-prober_proxy ###

### BEGIN /etc/grub.d/45_uefi-firmware ###
### END /etc/grub.d/45_uefi-firmware ###

### BEGIN /etc/grub.d/46_fwupd ###
### END /etc/grub.d/46_fwupd ###

### BEGIN /etc/grub.d/47_custom_proxy ###

# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.

### END /etc/grub.d/47_custom_proxy ###

### BEGIN /etc/grub.d/48_custom ###
if [ -f ${config_directory}/custom.cfg ]; then
source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/48_custom ###
mint@mint-System-Product-Name:~$

That isn't working. I don't use grub-customizer so I would have to to some research.
Have an other idea from looking at the grub.cfg file
copy the menu entry from post 45 into /boot/grub/custom.cfg

mint@mint-System-Product-Name:~$ sudo cp /etc/grub.d/48_custom /etc/grub.d/15_custom
[sudo] password for mint:
mint@mint-System-Product-Name:~$ sudo nano /boot/grub/custom.cfg
[sudo] password for mint:

(pasted)
menuentry "Linux Mint" --class ubuntu --class gnu-linux --class gnu --class os >
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,m>
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
linux /boot/vmlinuz root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro
initrd /boot/initrd.img
}
(saved)

mint@mint-System-Product-Name:~$ sudo update-grub
Sourcing file `/etc/default/grub'
Sourcing file `/etc/default/grub.d/50_linuxmint.cfg'
Sourcing file `/etc/default/grub.d/init-select.cfg'
Generating grub configuration file ...
Found linux image: /boot/vmlinuz-5.19.0-41-generic
Found initrd image: /boot/initrd.img-5.19.0-41-generic
Found linux image: /boot/vmlinuz-5.15.0-71-generic
Found initrd image: /boot/initrd.img-5.15.0-71-generic
Found MX 19.4 patito feo (19.4 ) on /dev/sda1
Found Microsoft Windows XP Professional on /dev/sdf1
Found linux image: /boot/vmlinuz-5.19.0-41-generic
Found initrd image: /boot/initrd.img-5.19.0-41-generic
Found linux image: /boot/vmlinuz-5.15.0-71-generic
Found initrd image: /boot/initrd.img-5.15.0-71-generic
Found MX 19.4 patito feo (19.4 ) on /dev/sda1
Found Microsoft Windows XP Professional on /dev/sdf1
done
mint@mint-System-Product-Name:~$

Same error...here is /boot/grub/grub.cfg in case you need to see it refreshed.

mint@mint-System-Product-Name:~$ cat /boot/grub/grub.cfg
#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
if [ "${initrdfail}" = 2 ]; then
set initrdfail=
elif [ "${initrdfail}" = 1 ]; then
set next_entry="${prev_entry}"
set prev_entry=
save_env prev_entry
if [ "${next_entry}" ]; then
set initrdfail=2
fi
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="MX 19.3 patito feo (19.3 ) (on /dev/sda1)"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function initrdfail {
if [ -n "${have_grubenv}" ]; then if [ -n "${partuuid}" ]; then
if [ -z "${initrdfail}" ]; then
set initrdfail=1
if [ -n "${boot_once}" ]; then
set prev_entry="${default}"
save_env prev_entry
fi
fi
save_env initrdfail
fi; fi
}
function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}

if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
font="/usr/share/grub/unicode.pf2"
fi

if loadfont $font ; then
set gfxmode=auto
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=en_US
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ] ; then
set timeout=30
else
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=hidden
set timeout=8
# Fallback hidden-timeout code in case the timeout_style feature is
# unavailable.
elif sleep --interruptible 8 ; then
set timeout=0
fi
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux_proxy ###

function gfxmode {
set gfxpayload="${1}"
if [ "${1}" = "keep" ]; then
set vt_handoff=vt.handoff=7
else
set vt_handoff=
fi
}
if [ "${recordfail}" != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if [ ${grub_platform} != pc ]; then
set linux_gfx_mode=keep
elif hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode



### END /etc/grub.d/10_linux_proxy ###

### BEGIN /etc/grub.d/30_os-prober_proxy ###
menuentry "MX Linux 19.4 patito feo (19.4 ) (on /dev/sda1)" --class mx --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-simple-6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro quiet splash
initrd /boot/initrd.img-4.19.0-14-amd64
}
### END /etc/grub.d/30_os-prober_proxy ###

### BEGIN /etc/grub.d/40_custom_proxy ###
menuentry "Linux Mint" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
linux /boot/vmlinuz-5.4.0-146-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro quiet splash $vt_handoff
initrd /boot/initrd.img-5.4.0-146-generic
}
### END /etc/grub.d/40_custom_proxy ###

### BEGIN /etc/grub.d/41_linux_proxy ###
submenu "Advanced options for Ubuntu"{
menuentry "Ubuntu, with Linux 5.19.0-41-generic" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.19.0-41-generic-advanced-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
echo 'Loading Linux 5.19.0-41-generic ...'
linux /boot/vmlinuz-5.19.0-41-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro quiet splash $vt_handoff
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.19.0-41-generic
}
menuentry "Ubuntu, with Linux 5.19.0-41-generic (recovery mode)" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.19.0-41-generic-recovery-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
echo 'Loading Linux 5.19.0-41-generic ...'
linux /boot/vmlinuz-5.19.0-41-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro recovery nomodeset dis_ucode_ldr
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.19.0-41-generic
}
menuentry "Ubuntu, with Linux 5.15.0-71-generic" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.15.0-71-generic-advanced-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
echo 'Loading Linux 5.15.0-71-generic ...'
linux /boot/vmlinuz-5.15.0-71-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro quiet splash $vt_handoff
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.15.0-71-generic
}
menuentry "Ubuntu, with Linux 5.15.0-71-generic (recovery mode)" --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-5.15.0-71-generic-recovery-245d8512-eee9-47a3-8dd9-17952920d509' {
recordfail
load_video
insmod gzio
if [ x$grub_platform = xxen ]; then insmod xzio; insmod lzopio; fi
insmod part_msdos
insmod ext2
set root='hd0,msdos5'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos5 --hint-efi=hd0,msdos5 --hint-baremetal=ahci0,msdos5 245d8512-eee9-47a3-8dd9-17952920d509
else
search --no-floppy --fs-uuid --set=root 245d8512-eee9-47a3-8dd9-17952920d509
fi
echo 'Loading Linux 5.15.0-71-generic ...'
linux /boot/vmlinuz-5.15.0-71-generic root=UUID=245d8512-eee9-47a3-8dd9-17952920d509 ro recovery nomodeset dis_ucode_ldr
echo 'Loading initial ramdisk ...'
initrd /boot/initrd.img-5.15.0-71-generic
}
}
### END /etc/grub.d/41_linux_proxy ###

### BEGIN /etc/grub.d/42_linux_zfs ###
### END /etc/grub.d/42_linux_zfs ###

### BEGIN /etc/grub.d/43_linux_xen ###

### END /etc/grub.d/43_linux_xen ###

### BEGIN /etc/grub.d/44_os-prober_proxy ###
menuentry "Microsoft Windows XP Professional (on /dev/sdf1)" --class windows --class os $menuentry_id_option 'osprober-chain-1470355270353BB4' {
insmod part_msdos
insmod ntfs
set root='hd5,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd5,msdos1 --hint-efi=hd5,msdos1 --hint-baremetal=ahci5,msdos1 1470355270353BB4
else
search --no-floppy --fs-uuid --set=root 1470355270353BB4
fi
parttool ${root} hidden-
drivemap -s (hd0) ${root}
chainloader +1
}





set timeout_style=menu
if [ "${timeout}" = 0 ]; then
set timeout=10
fi
submenu "Advanced options for MX 19.4 patito feo (19.4 ) (on /dev/sda1)"{
menuentry "Debian GNU/Linux (on /dev/sda1)" --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-4.19.0-14-amd64--6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro quiet splash
initrd /boot/initrd.img-4.19.0-14-amd64
}
menuentry "Debian GNU/Linux, with Linux 4.19.0-14-amd64 (on /dev/sda1)" --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-4.19.0-14-amd64--6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro quiet splash
initrd /boot/initrd.img-4.19.0-14-amd64
}
menuentry "Debian GNU/Linux, with Linux 4.19.0-14-amd64 (systemd) (on /dev/sda1)" --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-4.19.0-14-amd64--6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro quiet splash init=/lib/systemd/systemd
initrd /boot/initrd.img-4.19.0-14-amd64
}
menuentry "Debian GNU/Linux, with Linux 4.19.0-14-amd64 (recovery mode) (on /dev/sda1)" --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-4.19.0-14-amd64-root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro single-6e5181d4-1b59-40ff-8133-495a43ecbbd5' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 6e5181d4-1b59-40ff-8133-495a43ecbbd5
else
search --no-floppy --fs-uuid --set=root 6e5181d4-1b59-40ff-8133-495a43ecbbd5
fi
linux /boot/vmlinuz-4.19.0-14-amd64 root=UUID=6e5181d4-1b59-40ff-8133-495a43ecbbd5 ro single
initrd /boot/initrd.img-4.19.0-14-amd64
}
}
### END /etc/grub.d/44_os-prober_proxy ###

### BEGIN /etc/grub.d/45_uefi-firmware ###
### END /etc/grub.d/45_uefi-firmware ###

### BEGIN /etc/grub.d/46_fwupd ###
### END /etc/grub.d/46_fwupd ###

### BEGIN /etc/grub.d/47_custom_proxy ###

# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.

### END /etc/grub.d/47_custom_proxy ###
mint@mint-System-Product-Name:~$

SMG over on the Mint forum asked me....
Which distro is in control of grub?
By the way, you have a problem here and need to remove some kernels. That likely relates to the error.
Partition:
ID-1: / size: 229.17 GiB used: 48.09 GiB (21.0%) fs: ext4 dev: /dev/sda5
ID-2: /boot/efi size: 512 MiB used: 512 MiB (100.0%) fs: vfat dev: /dev/sda3

I told him dont really know which distro controls grub.

I ran "apt autoremove --purge" but not sure if it removed those kernels he mention.
mint@mint-System-Product-Name:~$ sudo apt autoremove --purge

Have you tried one of the entries in the grub submenu?

linuxmint is in control of the grub menu, I found that out when linuxmint became first in the boot order after the copy of the 40_custom_proxy to 15_custom_proxy. The problem is you have grub-customizer files in /etc/grub.d. You may have to install grub-customizer to fix.

A temporary fix would be to edit entries for linuxmint in the /boot/grub/grub.cfg file for the time being. This will hold up until a kernel update runs upddate-grub.

Well we've got something here! At boot, I drilled down into advanced options and selected "Ubuntu generic 21.19" and it booted into Mint without error. (Not sure why the advanced options all state ubuntu generic etc. but anyway...
I then installed Grub-Customizer (it was not currently installed) and in the customizer I moved the existing error prone "Linux Mint" boot option down into the advanced sub-menu and moved the "Ubuntu generic 21.19" (renamed it Linux Mint) up to the first boot option with MX Linux 2nd and works for me! Its working good enough for me! This old AMD64 is in my workshop and it just keeps on ticking! Im not surprised its gotten so confused as I have had just about every distro loaded on it at one time or another but kind of settled on Mint and MX.
Thanks for your patience and all of your help!
Should I call this solved!?

Great you got it working
Yes.