VNC Problem Proxmox 6.4

can you post the complete task log (double click on the failed console log) ?
 
bootdisk: virtio0
cores: 2
memory: 8192
name: XXXXXXX
net0: virtio=XXXXXXXXXXXX,bridge=vmbr0
numa: 0
onboot: 1
ostype: l26
scsihw: virtio-scsi-pci
smbios1: uuid=XXXXXXXXXXXXXXXXXXXX
sockets: 2
virtio0: ssd:150/vm-150-disk-0.qcow2,size=40G
 
proxmox-ve: 6.0-2 (running kernel: 5.0.15-1-pve)
pve-manager: 6.0-4 (running version: 6.0-4/2a719255)
pve-kernel-5.0: 6.0-5
pve-kernel-helper: 6.0-5
pve-kernel-5.0.15-1-pve: 5.0.15-1
ceph-fuse: 12.2.11+dfsg1-2.1
corosync: 3.0.2-pve2
criu: 3.11-3
glusterfs-client: 5.5-3
ksm-control-daemon: 1.3-1
libjs-extjs: 6.0.1-10
libknet1: 1.10-pve1
libpve-access-control: 6.0-2
libpve-apiclient-perl: 3.0-2
libpve-common-perl: 6.0-2
libpve-guest-common-perl: 3.0-1
libpve-http-server-perl: 3.0-2
libpve-storage-perl: 6.0-5
libqb0: 1.0.5-1
lvm2: 2.03.02-pve3
lxc-pve: 3.1.0-61
lxcfs: 3.0.3-pve60
novnc-pve: 1.0.0-60
proxmox-mini-journalreader: 1.1-1
proxmox-widget-toolkit: 2.0-5
pve-cluster: 6.0-4
pve-container: 3.0-3
pve-docs: 6.0-4
pve-edk2-firmware: 2.20190614-1
pve-firewall: 4.0-5
pve-firmware: 3.0-2
pve-ha-manager: 3.0-2
pve-i18n: 2.0-2
pve-qemu-kvm: 4.0.0-3
pve-xtermjs: 3.13.2-1
qemu-server: 6.0-5
smartmontools: 7.0-pve2
spiceterm: 3.1-1
vncterm: 1.6-1
zfsutils-linux: 0.8.1-pve1
 
yea i would upgrade your installation
 
no this should not affect your vms, but after a kernel upgrade you may need to reboot the host, so if you do not have a cluster,
you may want to plan some downtime to reboot