GRUB - configuration file parameter not respected

Pre-Release Discussion
1

I’ve recently installed the UM 26.04 LTS Resolute Racoon Daily Build from Nov 19 2025.

lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=26.04
DISTRIB_CODENAME=resolute
DISTRIB_DESCRIPTION="Ubuntu Resolute Raccoon (development branch)"

Related to the following file:

/etc/default/grub

For some reason, GRUB appears to be ignoring the settings for the following two parameters:

GRUB_COLOR_NORMAL="light-gray/black"

GRUB_COLOR_HIGHLIGHT="black/yellow"

which are recognized and used by my main system (UM 22.04.5 LTS) on my second internal disk.

The full contents of my configuration file are:

# If you change this file or any /etc/default/grub.d/*.cfg file,
# run 'update-grub' afterwards to update /boot/grub/grub.cfg.
# For full documentation of the options in these files, see:
#   info -f grub -n 'Simple configuration'

###
###	FUTURES:	Consider GRUB password via /etc/grub.d/40_custom 
###

###
###	Uncomment to limit probing for bootable OS on other disks or partitions
###
GRUB_DISABLE_OS_PROBER="false"


###
GRUB_DEFAULT=0


#GRUB_TIMEOUT_STYLE=hidden
GRUB_TIMEOUT_STYLE="menu"


#GRUB_TIMEOUT=0
GRUB_TIMEOUT=-1
GRUB_RECORDFAIL_TIMEOUT=-1


#GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo "UbuntuMATE 20.04 LTS" `
GRUB_DISTRIBUTOR=`( . /etc/os-release && echo ${NAME} )`


###
###	quirk specification is to suppress UAS for external USB3 drive operating on USB2 channel.
###
#GRUB_CMDLINE_LINUX_DEFAULT="resume=UUID=d6818877-fcce-4e10-b45c-17d5bf4670b8 quiet splash scsi_mod.use_blk_mq=1 usb-storage.quirks=1058:25ee:u usbcore.autosuspend=-1 ipv6.disable=1"
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash scsi_mod.use_blk_mq=1 usb-storage.quirks=1058:25ee:u usbcore.autosuspend=-1 ipv6.disable=1"


#GRUB_CMDLINE_LINUX=""
GRUB_CMDLINE_LINUX="verbose"


###
###	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_TERMINAL=console
GRUB_TERMINAL=gfxterm


###
###	The resolution used on graphical terminal
###	note that you can use only modes which your graphic card supports via VBE/GOP/UGA
###	you can see them in real GRUB with the command `videoinfo'
###
#GRUB_GFXMODE=640x480
GRUB_GFXMODE="1440x900,1280x1024,auto"


###
###	Set to text to disable graphics; set to keep to pass on any resolution/graphics mode
###
###	Positions correctly = NO
#GRUB_GFXPAYLOAD_LINUX="text"
#
###	Positions correctly = NO
#GRUB_GFXPAYLOAD_LINUX="auto"
#
###	Positions correctly = YES
GRUB_GFXPAYLOAD_LINUX="keep"


###
###	Used for gfxterm for grub Themes
###
#GRUB_THEME="/boot/grub/themes/Primitivistical/theme.txt"

###	BOOT splash background => solid colour.
#GRUB_BACKGROUND=""

###	BOOT splash background => first *.png under /boot/grub		(DEFAULT)
#GRUB_BACKGROUND="*.png"

###	BOOT splash background => specified image.
#GRUB_BACKGROUND="/boot/grub/BG__Login_00__Ubuntu-MATE_WordMark_Modifiedv2_1440x900.png"


###
###	BOOT Menu Color Styling	**  Note: run 'update-grub' update grub for these changes to apply.
###
###	Line that is not currently selected (FG/BG)
GRUB_COLOR_NORMAL="light-gray/black"

###	Line that is selected (FG/BG)
GRUB_COLOR_HIGHLIGHT="black/yellow"

###	Background for selection menu => specified image.
#GRUB_MENU_PICTURE="/boot/grub/BG__Login_00__Ubuntu-MATE_WordMark_Modifiedv2_1440x900.png"


# 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"

[Edit: Updated for UM 26.04 LTS instead of UM 22.04.5 LTS]

inxi -Fxxx

System:
  Host: OasisMidi Kernel: 6.17.0-5-generic arch: x86_64 bits: 64 compiler: gcc
    v: 15.2.0 clocksource: tsc
  Desktop: MATE v: 1.28.2 wm: marco v: 1.26.2 with: mate-panel
    tools: mate-screensaver dm: LightDM v: 1.32.0 Distro: Ubuntu 26.04
    (Resolute Raccoon)
Machine:
  Type: Desktop Mobo: ASUSTeK model: M4A78-E v: Rev 1.xx
    serial: 101048580000313 uuid: 00dc001e-8c00-01fc-92e5-0026188ab57a
    BIOS: American Megatrends v: 2603 date: 04/13/2011
CPU:
  Info: quad core model: AMD Phenom II X4 810 bits: 64 type: MCP
    smt: <unsupported> arch: K10 rev: 2 cache: L1: 512 KiB L2: 2 MiB L3: 4 MiB
  Speed (MHz): avg: 800 min/max: 800/2600 boost: disabled volts: 1.5 V
    ext-clock: 200 MHz cores: 1: 800 2: 800 3: 800 4: 800 bogomips: 20869
  Flags-basic: ht lm nx pae sse sse2 sse3 sse4a svm
Graphics:
  Device-1: Advanced Micro Devices [AMD/ATI] RS780D [Radeon HD 3300]
    vendor: ASUSTeK driver: radeon v: kernel arch: TeraScale ports:
    active: VGA-1 empty: DVI-D-1 bus-ID: 01:05.0 chip-ID: 1002:9614
    class-ID: 0300
  Display: x11 server: X.Org v: 21.1.18 compositor: marco v: 1.26.2 driver:
    X: loaded: radeon unloaded: fbdev,modesetting,vesa dri: r600 gpu: radeon
    display-ID: :0 screens: 1
  Screen-1: 0 s-res: 1440x900 s-dpi: 96 s-size: 381x238mm (15.00x9.37")
    s-diag: 449mm (17.69")
  Monitor-1: VGA-1 mapped: VGA-0 model: HP w1707 serial: CNC918Q23B res:
    mode: 1440x900 hz: 60 scale: 100% (1) dpi: 99 size: 370x230mm (14.57x9.06")
    diag: 436mm (17.2") modes: max: 1440x900 min: 720x400
  API: EGL v: 1.5 hw: drv: amd r600 platforms: device: 0 drv: r600 device: 1
    drv: swrast gbm: drv: r600 surfaceless: drv: r600 x11: drv: r600
    inactive: wayland
  API: OpenGL v: 4.5 compat-v: 3.3 vendor: mesa v: 25.2.6-1ubuntu1
    glx-v: 1.4 direct-render: yes renderer: AMD RS780 (DRM 2.51.0 /
    6.17.0-5-generic LLVM 20.1.8) device-ID: 1002:9614
  Info: Tools: api: eglinfo,glxinfo x11: xdriinfo, xdpyinfo, xprop, xrandr
Audio:
  Device-1: Advanced Micro Devices [AMD/ATI] SBx00 Azalia
    driver: snd_hda_intel v: kernel bus-ID: 00:14.2 chip-ID: 1002:4383
    class-ID: 0403
  Device-2: Advanced Micro Devices [AMD/ATI] RS780 HDMI Audio [Radeon
    3000/3100 / HD 3200/3300] driver: snd_hda_intel v: kernel bus-ID: 01:05.1
    chip-ID: 1002:960f class-ID: 0403
  API: ALSA v: k6.17.0-5-generic status: kernel-api
  Server-1: PipeWire v: 1.4.9 status: n/a (root, process) with:
    1: pipewire-pulse status: active 2: wireplumber status: active
Network:
  Device-1: Qualcomm Atheros AR8121/AR8113/AR8114 Gigabit or Fast Ethernet
    vendor: ASUSTeK driver: ATL1E v: N/A pcie: speed: 2.5 GT/s lanes: 1
    port: dc00 bus-ID: 02:00.0 chip-ID: 1969:1026 class-ID: 0200
  IF: enp2s0 state: up speed: 1000 Mbps duplex: full mac: 00:26:18:8a:b5:7a
Drives:
  Local Storage: total: 5.91 TiB used: 13.21 GiB (0.2%)
  ID-1: /dev/sda vendor: Western Digital model: WD5000AAKS-00V1A0
    size: 465.76 GiB speed: 1.5 Gb/s tech: N/A serial: WD-WMAWF0060756
    fw-rev: 1D05 scheme: MBR
  ID-2: /dev/sdb vendor: Western Digital model: WD20EZRX-00DC0B0
    size: 1.82 TiB speed: 3.0 Gb/s tech: N/A serial: WD-WCC300611350
    fw-rev: 0A80 scheme: GPT
  ID-3: /dev/sdc vendor: Western Digital model: WD40EDAZ-11SLVB0
    size: 3.64 TiB type: USB rev: 2.1 spd: 480 Mb/s lanes: 1 tech: HDD rpm: 5400
    serial: WD-WX32D60EUYRJ fw-rev: 4009 scheme: GPT
Partition:
  ID-1: / size: 455.41 GiB used: 13.21 GiB (2.9%) fs: ext4 dev: /dev/sda1
Swap:
  ID-1: swap-1 type: file size: 3.51 GiB used: 0 KiB (0.0%) priority: -2
    file: /swap.img
Sensors:
  System Temperatures: cpu: 53.0 C mobo: 41.0 C
  Fan Speeds (rpm): cpu: 2800 case-1: 0 case-2: 0
  Power: 12v: 12.44 5v: N/A 3.3v: 3.47 vbat: N/A
Info:
  Memory: total: 4 GiB note: est. available: 3.51 GiB used: 1.11 GiB (31.7%)
  Processes: 215 Power: uptime: 27m states: freeze,mem,disk suspend: deep
    wakeups: 0 hibernate: platform Init: systemd v: 257 default: graphical
  Packages: 2096 pm: dpkg pkgs: 2083 pm: snap pkgs: 13 Compilers:
    gcc: 15.2.0 Shell: Bash (sudo) v: 5.3.3 running-in: mate-terminal
    inxi: 3.3.39
1 Like
2

Perhaps consider filing a bug report?

3

Obvious question: Did you run sudo update-grub after changing /etc/default/grub?

Having said that, I have the same result as you on 24.04. According to my records, these days, instead of the old way of doing it, you need to tailor Grub using a theme. Here’s a simple how-to for basic formatting.

4

Thank you, Paddy.


Yes, I always do, and did, run update-grub after the changes.

I dug around and saw a log of stuff that seemed dated about themes (did that once 8 years ago) and about a custom config under /etc/default/grub.d/99_customcolours, and again for /etc/grub.d/custom.cfg, but I expected the basic (historical) parameters in the master /etc/default/grub file to still be in effect, which clearly they are not. :frowning:


Regarding that link, I have seen that before, but that doesn’t seem to apply, because the

/etc/grub.d/41_custom

script has the following logic related to customization:

#!/bin/sh
cat <<EOF
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
EOF
5

Well, I followed the instructions in the link, and it worked perfectly. But that’s in 24.04, not 26.04.

Try it to see what happens. It’s easy enough to undo if you don’t like it or it doesn’t work.

BTW, you don’t have to run grub2-mkconfig as per the instructions; I found that update-grub did the job.