[SOLVED] Unable to open console to Ubuntu 16.04 container on Proxmox 7.1 with systemd.unified_cgroup_hierarchy=0


Feb 8, 2022

I'm trying to install a new container with Ubuntu 16.04 on Proxmox 7.1.
According to https://pve.proxmox.com/pve-docs/chapter-pct.html#pct_cgroup_compat, it is possible with customized boot options.
I have followed recommendations and I can see that my kernel cmdline is properly updated.

However if I create a simple container with Ubuntu16 template, I get strange problems when I start it:
* I'm not able to open a console
* the Web interface of the node that runs the CT is not reachable anymore
* I'm not able to ssh anymore on the node
* The node is seen up by other node of the cluster
* rebooting the reboot (stopped the CT), and I'm able to reach again the node via Web interface and ssh

Is there a customization I have forgotten?


Was finally able to solve the problems.
1. As my node has not been moved to DHCP after installation (as it should), I've got a conflict of IP between my container and the host
2. tty console is not showing any logging. Switching to "/dev/console" solve the issue. And I can see message "A start job is running for Raise network interfaces"
3. thanks to https://forum.proxmox.com/threads/a-start-job-is-running-for-raise-network-interfaces.32936/, I have switch IPV6 from DHCP to SLAAC

After these 3 steps I was able to boot my Ubuntu 16 container properly !

Hope it could help the next one trying to do the same ...


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