The following error has occured on a number of our user's Proxmox installs when attempting to access the VM's console.

TASK ERROR: command '/bin/nc -l -p 5900 -w 10 -c /usr/sbin/qm vncproxy 101 2>/dev/null' failed: exit code 1

This is actually a very easy error to resolve. If you're running a Windows based desktop you'll need to install Java, please go to http://java.com and install it from there. Once installed this should resolve this error if you're on a Windows desktop. If you're running on a Linux based desktop please make sure you have sun-java6-plugin installed.

If this error continues to happen please open a support ticket and we'll figure the error out.