Proxmox server not booting kernel 6.17.9

[MajorP93]

Hello Proxmox community,

I have a headless Proxmox server that I just upgraded by running apt dist-upgrade - as usual.
One of the upgrades that got installed is the new kernel 6.17.9.
After rebooting the system I noticed that it is still running the old kernel 6.17.4-2.

I even tried pinning the kernel to the new version by running /usr/sbin/proxmox-boot-tool kernel pin 6.17.9-1-pve --next-boot but the issue still persists - after reboot the system is still running on 6.17.4-2.

I checked some logs but was not able to find any error.

Here is some info that might be relevant: proxmox server got upgraded from PVE 8 to PVE 9 in the past.
It is running on a ZFS mirror (root on ZFS), that I configured via Proxmox installer back when I set it up initially.

root@prox:~# apt list --installed | grep 6.17

WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

proxmox-headers-6.17.4-2-pve/stable,now 6.17.4-2 amd64 [installed,auto-removable]
proxmox-headers-6.17.9-1-pve/stable,now 6.17.9-1 amd64 [installed,automatic]
proxmox-headers-6.17/stable,now 6.17.9-1 all [installed,automatic]
proxmox-kernel-6.17.4-1-pve-signed/stable,now 6.17.4-1 amd64 [installed,auto-removable]
proxmox-kernel-6.17.4-2-pve-signed/stable,now 6.17.4-2 amd64 [installed,automatic]
proxmox-kernel-6.17.9-1-pve-signed/stable,now 6.17.9-1 amd64 [installed,automatic]
proxmox-kernel-6.17/stable,now 6.17.9-1 all [installed,automatic]
root@prox:~# proxmox-boot-tool status
Re-executing '/usr/sbin/proxmox-boot-tool' in new private mount namespace..
System currently booted with uefi
558A-C9B1 is configured with: uefi (versions: 6.14.11-5-pve, 6.17.4-2-pve, 6.17.9-1-pve)
WARN: /dev/disk/by-uuid/CBC1-2780 does not exist - clean '/etc/kernel/proxmox-boot-uuids'! - skipping
root@prox:~# uname -a
Linux prox 6.17.4-2-pve #1 SMP PREEMPT_DYNAMIC PMX 6.17.4-2 (2025-12-19T07:49Z) x86_64 GNU/Linux

Did anyone else encounter this issue?

Anything that I can do to further troubleshoot / fix it?

Thanks a lot in advance.

Best regards

 

[uzumo]

If the following conditions are met, it will normally boot with 6.17.9-1.

If you have pinned it, it will boot with the kernel you pinned.

root@pve2:~# proxmox-boot-tool kernel list
Manually selected kernels:
None.

Automatically selected kernels:
6.17.4-2-pve
6.17.9-1-pve

If you have pinned it, use the following command to unpin it.

proxmox-boot-tool kernel unpin

Can you boot your computer with PVE by selecting a specific kernel (6.17.9-1) at startup?
Even if pinned, it will boot with the specified kernel.

 

[MajorP93]

If you have pinned it, it will boot with the kernel you pinned.

Thanks for your reply!

In my case it seems to not behave as expected.
I know about the pinning and read the documentation around proxmox-boot-tool.

root@prox:~# proxmox-boot-tool kernel list
Manually selected kernels:
None.

Automatically selected kernels:
6.14.11-5-pve
6.17.4-2-pve
6.17.9-1-pve

Pinned kernel:
6.17.9-1-pve

As you can see the proxmox-boot-tool reports my desired kernel to be pinned.

Despite that I am greeted with the old kernel after rebooting, which is what I was trying to explain:

root@prox:~# uname -a
Linux prox 6.17.4-2-pve #1 SMP PREEMPT_DYNAMIC PMX 6.17.4-2 (2025-12-19T07:49Z) x86_64 GNU/Linux

As for the manual selection in boot menu:

As it is a headless server I currently have no monitor and keyboard attached to it.
I will try to select the kernel manually when I have the time to do so.

Anyways: the system unfortunately does not behave "normally" or as expected.
Before this round of updates I never had issues with booting the new kernel.
Seems to be a new issue.