GRUB_DEFAULT= any number works without saving.
The only value that doesn’t work is grub_DEFAULT=saved
This can’t be true, because in my last attempt with BTRFS exactly THAT didn’t work. It was saved, but there were errors when booting.
exactly what?
GRUB_DEFAULT= any number
GRUB_DEFAULT=2 did not bring anything.
This seems to be the same problem @olividir describes.
It has worked for me in the past. The only way you should get that error is if you set GRUB_SAVEDEFAULT=true which is a separate setting.
My guess would be that you set GRUB_DEFAULT=saved and GRUB_SAVEDEFAULT=true.
Then you changed GRUB_DEFAULT=2 but left GRUB_SAVEDEFAULT set to true which caused the error.
GRUB boot loader configuration
GRUB_DEFAULT=2
GRUB_TIMEOUT=3
This is how mine looks, I’ll reboot and take pick of grub to show you how it works.
If you are getting errors you could need to comment out this
# Uncomment to make GRUB remember the last selection. This requires
# setting 'GRUB_DEFAULT=saved' above.
#GRUB_SAVEDEFAULT=true
But I was getting error because I uncommented GRUB_SAVEDEFAULT=true
3 Likes
I definitely did NOT set that. That is exactly what keeps me away from BTRFS. It is exasperating. I have given up on it for now …
Exactly like that it looked with me (under BTRFS, as well as just now under ext4). Only hfunctions only with ext4. No idea which evil spirit has haunted my computer.
And this is how my grub looks like, it highlights the rolling kernel
And I am on BTRFS
But the choice is yours if you want BTRFS or ex4, or any other file system. 
1 Like
That’s how it looks with ext4 at the moment, but with BTRFS it just didn’t work. Will try it again in the near future.
If you want this results, and you have both lts and rolling kernel, then I suggest you have
GRUB_DEFAULT=2
And then just to be sure, you could run
sudo grub-mkconfig -o /boot/grub/grub.cfg
to make it stick
3 Likes
And make the line
#GRUB_SAVEDEFAULT=true
look exactly like this on BTRFS, if you don’t, you will get this error on boot
Booting 'EndeavourOS, on linux-lts'
error: sparse file not allowed.
Loading kernel linux-lts ...
Loading initial ramdisk ...
Press any key to continue...
That’s exactly what I did, but thanks for pointing it out! 
1 Like
The joke is that I had #GRUB_SAVEDEFAULT=true exactly like this and still got this error message.
#GRUB_SAVEDEFAULT=true is the default value, which I have left as it is.
Then I am unfortunately in too deep water to be able to help.
I have no idea how grub works… it’s all magic to me 
Then you feel the same way I do. I’ve been struggling with this problem since I first tried BTRFS 2 years ago.
1 Like
I have the feeling, that you are a little confused about the “grub can’t write on btrfs”
With btrfs you can make changes on grub via editing /etc/default/grub (here was an error) an updating grub via
sudo grub-mkconfig -o /boot/grub/grub.cfg
because at that moment you are in the booted OS an there are no writing problems with btrfs.
Only on the boot, before the OS, grub itself can’t write on btrfs.
Can you post you entire grub.cfg that we can search together, to find problems?
@arcDaniel Thanks for the explanation about grub.config.
I can’t do that at the moment as I am on ext4 now. My questions are aimed at what I can/must do better in a next attempt with BTRFS to not have this problem.
But grub.cfg is there no matter if you are on ex4 or btrfs.
Should be here
/boot/grub/grub.cfg
grub.congig:
#
# 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 ###
insmod part_gpt
insmod part_msdos
if [ -s $prefix/grubenv ]; then
load_env
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="0"
fi
if [ x"${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 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_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 52202e8d-3b7d-4997-ad57-75310aabf6f3
else
search --no-floppy --fs-uuid --set=root 52202e8d-3b7d-4997-ad57-75310aabf6f3
fi
font="/usr/share/grub/unicode.pf2"
fi
if loadfont $font ; then
set gfxmode=1024x768x32
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=de_DE
insmod gettext
fi
terminal_input console
terminal_output gfxterm
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 52202e8d-3b7d-4997-ad57-75310aabf6f3
else
search --no-floppy --fs-uuid --set=root 52202e8d-3b7d-4997-ad57-75310aabf6f3
fi
insmod png
background_image -m stretch /usr/share/endeavouros/splash.png
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=menu
set timeout=3
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
set timeout=3
fi
### END /etc/grub.d/00_header ###
### BEGIN /etc/grub.d/10_linux ###
menuentry 'EndeavourOS Linux, mit Linux linux-lts' --class endeavouros --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-linux-lts-advanced-52202e8d-3b7d-4997-ad57-75310aabf6f3' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 52202e8d-3b7d-4997-ad57-75310aabf6f3
else
search --no-floppy --fs-uuid --set=root 52202e8d-3b7d-4997-ad57-75310aabf6f3
fi
echo 'Linux linux-lts wird geladen …'
linux /boot/vmlinuz-linux-lts root=UUID=52202e8d-3b7d-4997-ad57-75310aabf6f3 rw loglevel=3 nowatchdog nvme_load=YES
echo 'Initiale Ramdisk wird geladen …'
initrd /boot/intel-ucode.img /boot/initramfs-linux-lts.img
}
menuentry 'EndeavourOS Linux, with Linux linux-lts (fallback initramfs)' --class endeavouros --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-linux-lts-fallback-52202e8d-3b7d-4997-ad57-75310aabf6f3' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 52202e8d-3b7d-4997-ad57-75310aabf6f3
else
search --no-floppy --fs-uuid --set=root 52202e8d-3b7d-4997-ad57-75310aabf6f3
fi
echo 'Linux linux-lts wird geladen …'
linux /boot/vmlinuz-linux-lts root=UUID=52202e8d-3b7d-4997-ad57-75310aabf6f3 rw loglevel=3 nowatchdog nvme_load=YES
echo 'Initiale Ramdisk wird geladen …'
initrd /boot/intel-ucode.img /boot/initramfs-linux-lts-fallback.img
}
menuentry 'EndeavourOS Linux, mit Linux linux' --class endeavouros --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-linux-advanced-52202e8d-3b7d-4997-ad57-75310aabf6f3' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 52202e8d-3b7d-4997-ad57-75310aabf6f3
else
search --no-floppy --fs-uuid --set=root 52202e8d-3b7d-4997-ad57-75310aabf6f3
fi
echo 'Linux linux wird geladen …'
linux /boot/vmlinuz-linux root=UUID=52202e8d-3b7d-4997-ad57-75310aabf6f3 rw loglevel=3 nowatchdog nvme_load=YES
echo 'Initiale Ramdisk wird geladen …'
initrd /boot/intel-ucode.img /boot/initramfs-linux.img
}
menuentry 'EndeavourOS Linux, with Linux linux (fallback initramfs)' --class endeavouros --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-linux-fallback-52202e8d-3b7d-4997-ad57-75310aabf6f3' {
load_video
set gfxpayload=keep
insmod gzio
insmod part_gpt
insmod ext2
set root='hd0,gpt2'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,gpt2 --hint-efi=hd0,gpt2 --hint-baremetal=ahci0,gpt2 52202e8d-3b7d-4997-ad57-75310aabf6f3
else
search --no-floppy --fs-uuid --set=root 52202e8d-3b7d-4997-ad57-75310aabf6f3
fi
echo 'Linux linux wird geladen …'
linux /boot/vmlinuz-linux root=UUID=52202e8d-3b7d-4997-ad57-75310aabf6f3 rw loglevel=3 nowatchdog nvme_load=YES
echo 'Initiale Ramdisk wird geladen …'
initrd /boot/intel-ucode.img /boot/initramfs-linux-fallback.img
}
### END /etc/grub.d/10_linux ###
### BEGIN /etc/grub.d/20_linux_xen ###
### END /etc/grub.d/20_linux_xen ###
### BEGIN /etc/grub.d/30_os-prober ###
### END /etc/grub.d/30_os-prober ###
### BEGIN /etc/grub.d/30_uefi-firmware ###
fwsetup --is-supported
if [ "$grub_platform" = "efi" -a "$?" = 0 ]; then
menuentry 'UEFI Firmware Settings' $menuentry_id_option 'uefi-firmware' {
fwsetup
}
fi
### END /etc/grub.d/30_uefi-firmware ###
### BEGIN /etc/grub.d/35_fwupd ###
### END /etc/grub.d/35_fwupd ###
### BEGIN /etc/grub.d/40_custom ###
# 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/40_custom ###
### BEGIN /etc/grub.d/41_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/41_custom ###
Currently the LTS kernel runs with ext4!