If GRUB is installed on a different device than the one that the BIOS boots from, the system may still boot as long as the device-installed GRUB is compatible with the OS-installed GRUB.
But once they diverge, GRUB may display messages like
“symbol ‘grub_term_highlight_color’ not found”
This does not apply systems booting via UEFI, only systems booting via BIOS can be affected.
On affected systems this problem becomes visible with UCS 4.1 Erratum #101, because it updates GRUB.
To correct this problem the BIOS boot order must match the GRUB configuration. This can be achieved by changing the BIOS boot order to boot from the disk that GRUB is installed on.
To achieve this, consult your devices BIOS configuration manual.
It can also be corrected by changing the disk(s) that GRUB is installed on.
To achieve this, boot the UCS system via an external boot CDROM/USB stick as described in SDB article 1358.
Afterwards run the following command as user ‘root’
dpkg-reconfigure grub-pc
Answer the questions shown by dpkg-reconfigure as follows:
- Question for “Linux command line”:
Press Return to keep the value as-is - Question for “default command line for Linux”:
Press Return to keep the value as-is - Question for “devices for GRUB installation”:
select the correct device(s) (i.e. the device(s) the BIOS is configured to boot from) to install GRUB on.
Multiple devices can be selected.
Please note:
Select only devices (e.g. /dev/sda), not partitions (e.g. /dev/sda1).
Do not select device mapper devices (e.g. /dev/dm-0). - Question for changed configuration file “/etc/default/grub”
Press Return to keep the configuration file as-is.
Using dpkg-reconfigure ensures that future GRUB updates will not lead to the same problem, as the device selection is saved for future GRUB updates to use.
Finally run
ucr commit /etc/default/grub
to make sure that file is correct.
This fix can be done before or after installing UCS 4.1 Erratum 101.
If the machine was rebooted after installing UCS 4.1 Erratum 101 and the system hangs with the aforementioned message, it should be possible to temporarily change the BIOS boot order to the disk that GRUB is installed on to boot into the system (e.g. by pressing F8 during the boot sequence).