Hello,
Have the problem with KDE Neon - user edition - 20240201-07:44 - KDE Neon 5.27 : no other OS installed.
Before the update : everything was OK and running well !
Installed on my older laptop ASUS K70IC with Nvidia GEFORCE GT 220M - CUDA - 1GB.
What I have to do to solve this : please in detail : I’m a beginner !
Thanks in advance for your reply.
Best regards.
Select a different kernel option from the grub boot menu.
Thanks, but how to realize this ?
I am not an expert, sorry.
You don’t have a boot menu?
If you aren’t seeing one, you will need to hit your key at the right spot past the initial bios/uefi splash - it can be tricky to find. it is for me.
the menu that comes up when you first boot should offer you Advanced Options or similar.
choose that and look for the kernel version just prior to the one that doesn’t work and boot into that.
you may just have to keep doing that until the fix whatever it was that got broke.
another option (also under the Advanced menu) is Recovery options
choose that and try to clean your system of uneeded files and reboot
go back a 2nd time and try to repair damaged packages and reboot
Single-boot systems won’t normally show a grub menu.
that seems like a bad idea.
grub should always at least flash on the screen during boot (1s is enough to “catch it”)
No not really. It’s a “set and go” thing. With me I keep pushing the ESC key during BIOS/UEFI splash screen. Every computer brand is different which key it is. But it’s one of the function keys if not ESC.
Once you figure it out, you might have to set your kernel permanently as default because some distros keep adding more and that defaults to the new one. grubby --set-default /boot/vmlinuz-(kernel name here.) [You have to go into Terminal for that. Hopefully it will work for your distro)
I dunno, most distros I have used seem to do this by default, and I usually single-boot my stuff.
I will guess the thought is that you don’t have much of a need for the menu normally in this use-case (theoretically, lol!). Plus all the complaints from the boot-speed fanatics, maybe? 
how do you get to the recover options then? or memtest?
You hit esc, or shift on legacy bios systems.
However, I will say that the use of these keys does not seem to be common knowledge, which doesn’t really help much.
Then again, how do you get to recovery mode in Windows?
Putting on my specualtion hat, the arguments from the distros and grub developers probably is that these are not things used very often, let alone available to most people - memtest didn’t even support efi or secure boot until quite recently. So they likely say that it makes no sense to have a menu for single OS systems.
Thinking back, anecdotally, as a single-booter on 4 of my 5 systems, I think I have used recovery mode once, maybe twice in the past two years, and chose a different kernel or boot option edit maybe a half dozen? And memtest, I can’t say I have ever used it at all in recent decades, definitely not since my last “legacy” BIOS system went away. Again, this is anecdotal.
i’m using one of those legacy systems… my disks are MBR and my motherboard barely supports EFI at all ( can get a menu by hitting F12, but that’s the extent of it).
since installing kubuntu almost a year ago, there have been two occasions where i need to roll back a kernel update and each time the grub menu is what saved me from having to do what every windows user dreds… find their recovery CD.
i was able to quickly identify the boot partition was full of useless junk and using the clean up function in the recovery menu allowed me to boot again as it deleted all the extra kernals that came in with the update.
one of the strengths of linux is that it’s easier to recover from things like this than windows would be.
You may have already found the answer to this, but you have to hold down the, I think, right Shift key, right after you turn on your computer. Then the Grub boot menu will appear. You could hold down both Shift keys just for to be sure. Anyway, that gives you a menu, and the 2nd item will be “Advanced boot options” or something similar. From there, you will see pairs of options.
This page covers what to do in more detail. Since KDE neon is based on Ubuntu, I just searched for “ubuntu boot menu help” and got what you need:
you could have this problem:
Workaround: do not use Discover or pkcon, do apt full-upgrade and always manually apply update-grub after an upgrade. This is a known issue and on the radar of neon developers.