Unable to open pty: No such file or directory

Udev is a dependency of xorg and other development packages that breaks OpenVZ containers if installed or upgraded.

Re-create the missing devices after an upgrade via:

vzctl exec {VEID} /sbin/MAKEDEV tty
vzctl exec {VEID} /sbin/MAKEDEV pty

For a permanent fix, edit /etc/rc.sysinit to disable udev and auto-repair the devices:

/sbin/MAKEDEV tty
/sbin/MAKEDEV pty