Hi,
I got the same error message. Unfortunately update & dist-upgrade didn't work for me.
root@baluNUC:~# pveversion
pve-manager/6.4-13/9f411e79 (running kernel: 5.4.140-1-pve)
root@baluNUC:~# pveversion -v
proxmox-ve: 6.4-1 (running kernel: 5.4.140-1-pve)
pve-manager: 6.4-13 (running...