If try to restore the backups taken on another server the restoration completes but the contents are not restored actually. The issue is because the 'admin' user guid is different on every Plesk Panel installation, but the dump XML file contains the guid from a server where it was taken. To solve this issue we have to substitute the guid value in all the related backup '.xml' files:
server ~$ mysql -u admin -p`cat /etc/psa/.psa.shadow` psa -Ne"select guid from clients where id=1"
+--------------------------------------+
| ae6b85ab-2af7-422d-adfd-eb1fbb8173c6 |
+--------------------------------------+
server:~$ sed -i 's/e2047e7e-4bfa-4901-ae87-226a433a2d03/ae6b85ab-2af7-422d-adfd-eb1fbb8173c6/g' /var/lib/psa/dumps/*<backup_id>.xml
