Not sure why this has been thrown.It just gives a bunch of warnings like:
warn [-e] Virtfs mountpoint failed to umount: /home/virtfs/USER/var warn [-e] Virtfs directory "/home/virtfs/USER/var" was not umounted properly, not removing
====cPanel Docs about VirtFs=======
At this moment, I recommend you to post a cPanel ticket. Johnson, Did you post your ticket with cPanel already?