The customer creates a backup, but it does not contain the site's content upon completion.
Failed to pack files server_backup_... Warning: hosting "demo.com" /bin/tar: /tmp/fileBCmvZe: No such file or directory /bin/tar: Error is not recoverable: exiting now
Backups and chrooted shell access for FTP users may work improperly on CloudLinux Server OS if the cagefs package is installed and enabled for all users. When Plesk backup uses 'su', cagefs makes "chroots" (without actually using chroot() system call) into /usr/share/cagefs-skeleton and because of that "chrooting", files in /tmp are inaccessible and error occurs. Such modification to 'su' is done by adding module pam_lve to '/etc/pam.d/su'.
Remove pam_lve from /etc/pam.d/su.
Disabling pam_lve in /etc/pam.d/su will not affect cron jobs/etc., it will only affect su commands. Basically, it has no negative security implications at all.