Grub is missing Kubuntu?

[Wobbelblob]

So, after fixing my display problems, I've come to my last problem: For whatever reason, my regular grub does not recognize Kubuntu. My (current) main OS is Bazzite, which shows normally in GRUB, as well as another Linux OS and Windows. Kubuntu however is missing. To start it, I need to go into the UEFI to specifically boot the drive containing Kubuntu (all OS are installed on different drives). Which opens a slightly different looking GRUB version (apparently my Bazzite/other OS use Grub 2.12 while Kubuntu uses something more current?) which contains Kubuntu, but is missing Bazzite.

I've tried to update my GRUB, but ran into the problem that the command

sudo update-grub

doesn't work. The advanced command

sudo grub-mkconfig -o /boot/grub/grub.cfg​

also doesn't work and throws the same error that the command doesn't exist. I've then found this thread: https://askubuntu.com/questions/4186...mand-not-found, but that solution doesn't work for me, as on Bazzite that folder is not alterable, so I cannot add that specific .sh script. Any ideas for this?


Edit: If I use the

sudo update-grub

command on Kubuntu it doesn't throw the error about missing command and instead throws the following result:

error: syntax error.
error: Incorrect command.
error: syntax error.
Syntax error at line 243
Syntax errors are detected in generated GRUB config file.
Ensure that there are no errors in /etc/default/grub
and /etc/grub.d/* files or please file a bug report with
/boot/grub/grub.cfg.new file attached.
​

[die.boer]

lets 1st fix Kubuntu's grub error: run this in Kubuntu and post output please

sudo nano /boot/grub/grub.cfg.new