Removing "generic" kernel for 24.04 from Ubuntu 26.04 removes important packages

Support and Help
1

System

Fresh installation of Ubuntu Desktop 26.04, without TPM-backed encryption.

Confirmed on three independent installations: Two VMs and one bare metal.

Observation

Two “generic” kernels are installed:

  • linux-generic-hwe-24.04 : marked as manually installed
  • linux-generic-hwe-26.04 : marked as automatically installed

I thought, “I’ll remove linux-generic-hwe-24.04 because I don’t need it. I’m using 26.04, not 24.04”

I checked with --dry-run that nothing else would be removed, and it wouldn’t.

So…

$ sudo apt remove linux-generic-hwe-24.04

The hidden problem

The hidden problem is that linux-generic-hwe-26.04 is marked as automatically installed, and it’s a transitional stub that depends on linux-generic-hwe-26.04. So, when you next run autoremove, look at what is removed:

$ sudo apt autoremove
REMOVING:                       
  amd64-microcode  ieee-data        libbpfcc        linux-generic-hwe-26.04          python3-bpfcc    ubuntu-kernel-accessories
  bpfcc-tools      intel-microcode  libclang-cpp21  linux-headers-generic-hwe-26.04  python3-netaddr
  bpftrace         iucode-tool      libclang1-21    linux-image-generic-hwe-26.04    thermald

Question

Unless I’m misunderstanding something, this is a problem, isn’t it?

If not, why isn’t it a problem?

Shouldn’t we have linux-generic-hwe-26.04 marked as manually installed so that it’s not automatically removed?

Ubuntu Weekly Newsletter Issue 962
2

You stepped right into a classic metapackage trap!

What happened here is pretty straightforward: on 26.04 right now, linux-generic-hwe-24.04 is just a transitional dummy package that points to linux-generic-hwe-26.04. But because the installer seeds marked the 24.04 dummy as “manual” and the 26.04 package as “auto”, removing the 24.04 package made APT think nobody needs the 26.04 kernel anymore. So autoremove swept away your kernel, headers, and ubuntu-kernel-accessories, which dragged your CPU microcode and thermald down with it.

To get your kernel and microcode back and keep them safe from autoremove-

sudo apt install --reinstall linux-generic-hwe-26.04 intel-microcode amd64-microcode

And back to your question - yes, this is 100% a bug in the 26.04 development seeds. The installer shouldn’t leave an old 24.04 stub as the only root anchor for the kernel tree. It’s definitely worth running ubuntu-bug ubuntu-meta to file a quick bug report so the desktop team can update the seeds for 26.04.

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3

Thank you for confirming my suspicions!

I’ll create a bug report tomorrow, and report back here with the link.

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This returns the error, “This problem cannot be reported: This report is about a package that is not installed.”

I tried selecting “Other”, but it wouldn’t allow me to. I tried selecting “Installation”, but after asking me for my password four times, it got stuck on “Collecting problem information” (I tried this on two different devices, one VM and one bare metal).

Apport
Apport614×195 13.6 KB

This usually takes two or three minutes. After waiting 40 minutes (on one machine) and 50 minutes (on another), I gave up.

Do you have a better suggestion for reporting the problem?

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Ah, that’s on me Paddy, sorry! :face_with_peeking_eye:
I should have warned you that ubuntu-meta is only a source package name, while Apport strictly checks for installed binary packages like ubuntu-desktop. That’s why it complained about it not being installed, and the installer hook in 26.04 right now tends to hang forever trying to gather subiquity logs.

The easiest way around this is to either file it directly via the web form at OpenID transaction in progress or run ubuntu-bug ubuntu-desktop (or ubuntu-bug linux-generic-hwe-26.04).

Since both of those are actual binary packages on your system, Apport finishes in about five seconds without freezing.

For the bug description, you can just paste the exact sequence from your first post: clean 26.04 install marks the 24.04 dummy as manual, the real 26.04 kernel ends up as auto, and removing the dummy wipes the kernel and microcode on autoremove.

Once you file it, drop the link here and I’ll be glad to jump in and add my confirmation!

6

Thank you, Viktor

I used your suggestion for the title, as it’s easier to understand than mine.

The bug report is here:

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I subscribed to the bug and left a note with the APT dependency breakdown :wink:

I checked the package metadata on my Resolute test system, and your diagnosis is right - linux-generic-hwe-26.04 has no other reverse dependencies in the archive except that 24.04 stub. So removing the stub leaves the real kernel orphaned, and autoremove sweeps it away along with the CPU microcode.

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