Aborted, Failed to run cp command during backup generation..[365] [5009]

Hi,
I am facing problem while backup any website.

Following error is thrown during backup process
Aborted, Failed to run cp command during backup generation…[365] [5009]

And in the backup directory of the website being backed up, a public_html forlder and a meta.xml file is found. No DBs or anything else

Any suggestion
Regards
Rizwan