Grub misrecognizes Linux partition after update

[GerdG]

I am running a multi boot system with Linux Mint and Windows 10 without any problems for some years.

A few days ago I got an update of grub which recreates the boot menu but misrecognizes Linux Mint 20.2 as "Ubuntu". (first bug)

Then I started the "Grub Customizer" to look at the boot menu and maybe correct it but that responds with several syntax errors and "Failed saving grub configuration" (see screenshot) and asks to file a bug report here. (second or follow-up bug)

YFI:
I changed from HDD to a SSD a few months ago and kept the "old" HDD as a second drive since I didn't need the space. So don't be surprised that there currently are two Linux and two Windows.

sda1: Windows 10
sda5: Linux Mint 20.2
sdb2: Windows 10 (old)
sda6: Linux Mint 20.2 (old)

The Linux Mint in sda5 is now named "Ubuntu" in the grub startup.

Attached are two screenshots and the file grub.config.new as requested by the tool.

[Daniel Richter (danielrichter2007)]

The syntax error comes from a duplicated script code entry inside the "Advanced options for Linux Mint". You should be able to see it when selecting View -> [x] show placeholders. When removing it, you should be able to save the config.

Alternatively, by using the revert button on the top right, the problem should disappear as well.

Just wondering how to come to that situation. As long as the placeholders are hidden, grub customizer isn't moving script placeholders into submenus...

[GerdG (gerdg)]

Hi David
thank you for your answer.
I suppose the root cause was the update of grub. That changed the boot menu and even "renamed" Linux Mint to Ubuntu. This update seems to have messed up the configuration files created by your Grub Customizer before. Maybe there is some incompatibility between you and the present grub version?

Now I did revert everything, rebooted and now it seems to be OK.
Hopefully that it will still be OK when I adapt the grub menu by your Grub Customizer again.
Thanks.

Bye,
Gerd

[GerdG (gerdg)]

The grub boot menu after the revert seems to be OK, just not in the order I like. It shows both Linuxes correctly as Mint.
But starting grub customizer presented a (at least for me) correct looking structure but again identified my Linux Mint as "ubuntu". So I quit without update.

Questions:
Where does this "ubuntu" come from?
Is this a error still originating from the former corrupt(?) grub config files?
Do I have to delete some config files to really have a clean grub menu to begin with?
Or is there some incompatibility between the updated grub version and the customizer?

[Daniel Richter (danielrichter2007)]

Either this comes from linux mint, if its (inactive) grub is modified too (by running grub customizer there, you may revert it on this system too, in this case), or it's just a general problem of the os-prober (which is part of grub 2, not grub customizer) - in this case, the problem also exists without using grub customizer.

[GerdG (gerdg)]

I tried now manually grub mk-config.
There already is the wrong menuentry "ubuntu" which in reality is Linux Mint:
    menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-78393152-82ab-40fd-a659-eb7649202665'

os-prober doesn't even find my presently running Mint on sda5 but everything else:
/dev/sda1:Windows 10:Windows:chain
/dev/sdb1:Windows Recovery Environment:Windows1:chain
/dev/sdb2:Windows 10:Windows2:chain
/dev/sdb6:Linux Mint 20.2 Uma (20.2):LinuxMint:linux

Something is terribly gone wrong here since the last update of grub.
I don't have a clue how to fix it. Do you have any hints?

But I think this ticket can be closed since the root cause seems to be grub itself. Your grub customizer is just the place where the error becomes visible to me. :-(