Downgrade to kernel 5.4.0 because kernel 5.8.45 doesn't like my bluetooth controller

Question

I had no bluetooth issues with kernel 5.4.XX until I updated to kernel 5.8.0. I can't select 5.4.XX from Grub, is not there.

If I type dpkg --list | grep linux-image | grep ^ii on the terminal that's the result:

ii  linux-image-5.8.0-38-generic               5.8.0-38.43~20.04.1                   amd64        Signed kernel image generic
ii  linux-image-5.8.0-40-generic               5.8.0-40.45~20.04.1                   amd64        Signed kernel image generic
ii  linux-image-generic-hwe-20.04              5.8.0.40.45~20.04.25                  amd64        Generic Linux kernel image

How can I downgrade to the latest kernel 5.4.xx again?

Solution

Run in a terminal

sudo apt install linux-generic

This will install the latest 5.4 Ubuntu kernel.

Then reboot and select a 5.4 kernel in advanced options of grub menu.

Then remove the 5.8 kernel packages including headers, modules and modules-extra

Comments

[FeDos]

How do I remove 5.8 kernel?

[Pilot6]

Remove the kernel packages using synaptic or apt remove

[FeDos]

I never removed a kernel and I don't want to make a mess. Should I type sudo apt remove linux-image-5.8.0-38-generic?

[Pilot6]

This is correct. But it is better to remove first ` sudo apt remove linux-modules-extra-5.8.0-38-generic linux-modules-5.8.0-38-generic`. The same with headers.

[Pilot6]

Check the installed packages the same as you did, but not linux-image, but linux pattern.

[FeDos]

What about Linux-images? Should I remove that packages as well?

[Pilot6]

First remove modules, then images and headers.

[FeDos]

I did it as you said, then restarted with my finger crossed. Everything went fine but I can still see 5.8.xx if I type dpkg --list | grep linux- in the terminal

[Pilot6]

I am doing this almost every day ;-)

[Pilot6]

Look if they are installed ii. If not, then it's OK.

[FeDos]

ii linux-hwe-5.8-headers-5.8.0-48 ii linux-hwe-5.8-headers-5.8.0-40

[Pilot6]

So remove the headers too. They won't cause harm, but they will get update and occupy space.

[FeDos]

imgur.com/a/PyKcmLd thanks a lot!

[Pilot6]

All looks great