How do I uninstall a problematic kernel?

Question

Running Ubuntu 18.04 LTS I got a notice that an upgrade was needed and I consented. The upgrade updated my kernel from 5.4.0-91-generic to ...-92 and broke things. I can still boot to ...91 from GRUB.

I'm unable to spend any more time trying to resolve the upgrade problem at this time and would like to just uninstall it. However, I realize uninstalling is not the same a reverting and I am reluctant to just uninstall the ...92 upgrade as other things may be lost.

What can I do to remove the ...92 upgrade and get my machine back without damaging the OS?

The machine boots and I can SSH into it.

score 4 · Answer 1 · edited Jan 08 '22 at 10:47

It is better to do that without a GUI. GRUB is too important for me to trust a program which hides what it is doing exactly behind a GUI.

First, create a backup of the /etc/default/grub file:
```
cp /etc/default/grub $HOME
```
Now, open /etc/default/grub with a text editor and add:
```
GRUB_DEFAULT=saved
GRUB_SAVEDEFAULT=true
```
Update GRUB to save the changes:
```
sudo update-grub
```
Reboot to your working kernel, so that GRUB can save your choice for the next reboot.
Now, list all the kernel packages:
```
dpkg -l | egrep linux-'[g|i|m|h]'
```
Once identified, you can remove any kernel package with 5.4.0-92 in its name (e.g. linux-image-5.4.0-92-generic, linux-headers-5.4.0-92, linux-modules-extra-5.4.0-92-generic, linux-modules-5.4.0-92-generic) via apt remove.
If you want to avoid the problematic kernel coming with a future update, then run:
```
sudo apt-mark hold linux-image-generic linux-headers-generic
```
This will put a hold on the current linux-image-generic package and stop it from being updated.

You can undo it with:
```
sudo apt-mark unhold linux-image-generic linux-headers-generic
```
but you may not want to do this, as it's possible that the following kernel update will boot without problems, and this stops the kernel from being updated to a newer version.
To avoid that your running kernel gets uninstalled by apt autoremove, you can mark the kernel and header versions you want to keep on your system as manual. In your case the version you want to keep using is 5.4.0-91, so:
```
sudo apt-mark manual linux-image-5.4.0-91-generic linux-headers-5.4.0-91-generic
```

Error404 · Answer 2 · 2022-01-09T09:00:49.547

Graphical User Interface

You can do that using the grub-customizer Package. You can install it using:

sudo apt install grub-customizer

After installing the package you can launch the application using:

grub-customizer

You'll get an interface like:

Right-click on the kernel causing errors( 5.4.0-92-generic), and select remove:

Now, right-click on the working kernel ( 5.4.0-91-generic) and select move up:

Click on the save button to save the changes:

After doing the above run this in a terminal:

sudo update-grub
sudo apt autoremove

That's it!

Reference

Note: To get support and correct drivers for the device I'm using Ubuntu 21.10 with a custom kernel. Don't mind the kernel versions in the image, they're just for reference.

How do I uninstall a problematic kernel?

2 Answers2

Graphical User Interface