No permissions to create files

hi, i’m trying to restore a backup, and i think that i’m encounter a bug.
This is a log extrapolation '2020-02-20 17:22:35: ERROR: No permissions to create files in “/mnt/”.
I’m trying to restore the backup to a destination host different from the backup host.
I mounted the root volume in /mnt and call the restore with this command
‘urbackupclientctl restore-start -b last -m / -t /mnt/’,
before this, i changed the hostname with the same of the start host and copied the tokens folder in /usr/loca/var/urbackup/tokens.

I have the same issue.

I fixed by change premissions to 777:
chmod 777 /mnt
then run
urbackupclientctl restore-start -d rootfs -b last -m / -t /mnt

It’s very strange because I run urbackupclientctl from root.
And urbackupclientbackend.service runs from root too.