backup_restore_helper utility returned incorrect result. Extension with ID XX cannot be backuped.
When you try to backup your domains via Plesk Backup you may get some errors regarding sxtensions that have problems/errors/ or some misconfiguration and etc…
In my case i had problem in Plesk 17 with extension ID 9 – this is the error that i got:
backup_restore_helper utility returned incorrect result. Extension with ID 9 cannot be backuped. Please, contact your service provider
The issue was caused by looped symlinks in Plesk Migrator extension.
[root@server ~]# find /usr/local/psa/var/modules/panel-migrator/ -type l /usr/local/psa/var/modules/panel-migrator/sessions/sessions
[root@server ~]# ll /usr/local/psa/var/modules/panel-migrator/sessions/sessions lrwxrwxrwx 1 root root 50 Jul 24 03:11 /usr/local/psa/var/modules/panel-migrator/sessions/sessions -> /usr/local/psa/var/modules/panel-migrator/sessions
/usr/local/psa/var/ , afterwards affected extension was backed up successfully.
Check if the problem is resolved:
/usr/local/psa/bin/sw-engine-pleskrun /usr/local/psa/admin/sbin/backup_restore_helper --backup-extension 9 -object-type server
To see the debug log you need to activate it with help of this post.
P.S. If you got an unused extension in your server or extensions that you used them only couple of times , i think the recommendation is to remove them and save some headache in the feature.