[SOLVED] LXC containers fail to start after upgrading to 8.4.16

k.kateliev

New Member
Jan 4, 2026
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Hello everyone,

I just upgraded my main PVE server from 8.4.14 to 8.4.16, rebooted and now LXC won't run any of my containers.

Code:
lxc_spawn: 1738 Permission denied - Failed to clone a new set of namespaces
__lxc_start: 2114 Failed to spawn container "101"
TASK ERROR: startup for container '101' failed

I found some information that this is related to a known bug in LXC itself, but what is stranger is that my repositories somehow got messed up:
1767555207900.png

I first ran 'apt-get update' and 'pveupgrade' on my backup PVE node and all went fine there. But here, on my main node, something went horribly wrong during upgrade, I've got no idea what it was, and I have started running in circles already. Any help would be appreciated.

Cheers!
 
OK, I just figured something out. Somehow, I managed to get my node upgraded to Trixie. And I guess there's no safe return back to Bookworm?
 
Hello,

Downgrading to an older Proxmox VE version is not supported. The only recommended way to go back to Bookworm would be to reinstall Proxmox VE from the 8.4 ISO.

My recommendation would be to take a look at the Proxmox VE 8 to 9 upgrade guide at our wiki [1]. Perhaps, and depending on how did the machine upgraded to trixie you can fix the situation.

Why do you think you are running on Trixie? On the screenshot I only see bookworm repositories. Whats the output from the commands `cat /etc/os-release` and `pveversion`?

[1] https://pve.proxmox.com/wiki/Upgrade_from_8_to_9
 
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I suggest you start doing bare-metal backups of PVE host if you ever have to downgrade. " Relax and Recover " is a useful tool for this and will also recreate LVM layout, but I also have custom fsarchiver scripts from back-in-the-day crunchbang
 
Hi guys, thank you for replying. I already went down that route last night, shortly after posting. Wiped out the whole server, re-installed PVE 8.4.16 from scratch, updates the packages to their latest versions, re-configured the system again and restored all my VM's and LXC's from PBS.
 
Why do you think you are running on Trixie? On the screenshot I only see bookworm repositories. Whats the output from the commands `cat /etc/os-release` and `pveversion`?

[1] https://pve.proxmox.com/wiki/Upgrade_from_8_to_9
Because, after my first post, something in that repository mess-up made me think I upgraded the Linux "underneath" PVE. So I checked the version of Linux and, indeed, it showed as Trixie (version 13).
I just took for granted that PVE has its Linux build pinned, so I can't upgrade it by mistake. Alas, I found out the hard way, that this isn't true. :)

Anyway, problem solved.
 
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