vzquota : (error) Quota on syscall for xxx: Device or resource busy

Error: vzquota : (error) Quota on syscall for xxx: Device or resource busy
Note: Imagining 63583 as the Container ID

# vzctl restart 63583
Restarting container
Starting container ...
vzquota : (warning) quota usage is invalid for id 63583, recalculating disk usage...
vzquota : (error) Quota on syscall for id 63583: Device or resource busy
vzquota : (error)       Possible reasons:
vzquota : (error)       - Container's root is already mounted
vzquota : (error)       - there are opened files inside Container's private area
vzquota : (error)       - your current working directory is inside Container's
vzquota : (error)         private area
vzquota : (error)       Currently used file(s):
/vz/private/63583/etc
vzquota on failed [3]

The error message indicates 2 things:
1) There are some files in open state inside the VPS private area. You can check if there are any open files by executing:
 lsof 2> /dev/null | egrep '/vz/root/63583/|/vz/private/63583/'
where, 63583 is the VPS ID. It will list the open files which you can close and start the VPS.
2) Your current working directory on the host server is inside the VPS’s private area i.e. the private area of the VPS is at /vz/private/xxx and your current working directory while starting the VPS is inside /vz/private/xxx.
Check the current working directory:

root@server [~]# pwd

if the working directory is inside the VPS’s private area, come out of that directory by just executing the command

root@server [~]#  cd

This will bring you out to the home directory of the root user and you will be able to start the VPS without any issues.

root@server [~]# vzctl start VEID