As a normal practice, it is a good idea to not reboot to solve problems on a Linux system, because Linux systems are usually quite stable, and issues, if not directly kernel related (very rare except under kernel or module development and testing), then it is a service that can be restarted. After an update, that messed up, you have to make sure it put everything back the way it should be so it can boot back up if you are going to reboot. It may have hosed your /dev/ directory and stuff in it. It could be the result of a broken udev or makedev install.

At this point you would need console access, say via command console on webmin or whm, and execute foolowing command :
# /sbin/MAKEDEV pty
# /sbin/MAKEDEV tty
this’s just temporary solotutions, the eror will back after your VPS reboot.

To Fix this issue permanently,

1. Edit the file /etc/rc.sysinit of the VPS server

2. Comment the line
#/sbin/start_udev

3. Add the following lines after /sbin/start_udev:

/sbin/MAKEDEV tty
/sbin/MAKEDEV pty

4. Reboot your VPS