This could be an issue connected to
GRUB_RECORDFAIL_TIMEOUT. According to the official Ubuntu documentation—which is still relevant to Lubuntu—it says:
If the last boot failed or after a boot into Recovery Mode the menu
will be displayed until the user makes a selection.
To change this behaviour, edit /etc/default/grub and add the variable
GRUB_RECORDFAIL_TIMEOUT. Set the value similar to setting for
- For -1, there will be no countdown and thus the menu will display.
- For 0, menu will not display even for a failed startup.
- For >=1, menu will display for the specified number of seconds.
Run update-grub after the change have been made.
It could be that your setup is somehow just powering down and/or rebooting Lubuntu in a way that makes it feel that the last boot failed—or the system crashed—thus it’s going to look for the
GRUB_RECORDFAIL_TIMEOUT value and use it’s default value if it’s not set elsewhere.
Regardless, here is how I tweak that
First, open up
nano—or you can use whatever text editor you like—like this:
sudo nano /etc/default/grub
Then I set
GRUB_TIMEOUT and then
GRUB_RECORDFAIL_TIMEOUT like this:
Note that I am setting
GRUB_RECORDFAIL_TIMEOUT with a variable reference to
$GRUB_TIMEOUT instead of setting a new number; feel free to change that to a real number if you need different timeout values.
Then I update GRUB and all should be good: