Error "could not set polling interval for ballooning - VM 300 qmp command 'qom-set' failed - client closed connection"

[jawsgee]

Hi all,

I ran into an issue where none of my VMs would start after rebooting my Proxmox server. For context, after the reboot, vmbr0 was missing when I checked with ip a, and the Proxmox web UI was also unavailable. I had to manually start the required services using systemctl. Once things were back up, I found that none of my VMs would start. When attempting to start a VM, I receive the following error:

could not set polling interval for ballooning - VM qmp command 'qom-set' failed - client closed connection


Here's the my vm config:


I am new to proxmox so any help is appreciated! Thank you in advance!

 

[j.theisen]

Hi @jawsgee

thanks for posting in the forum!

This is very unusual and unexpected behavior.
Did you install this host recently? What method did you use, i.e. ISO or Debian and manually install PVE on top of that?

To gather a bit of information please post the output of the following commands:

• pveversion -v
• journalctl --since "2026-06-18 08:00" --until "2026-06-19 16:00"
  Please adapt the timestamps accordingly to the time before the reboot and crash and now
• cat /etc/network/interfaces

Are other VMs also affected or is it just this VM 300?

Yours sincerely
Jonas