Backup not working any more

When I run Backup on my system using OS ubuntuMATE 16.04-3 and ubuntu17.10 it has always worked. I haven’t changed anything (to my knowledge) and now it fails on both systems. Receive message “Failed to mount Windows share: Invalid argument”. I noticed in the logs that mkdir failed on directory /var/cache/samba: Permission denied on the 17.10 system.
Help Please,
Don

on 10/14/2017 I also found on 16.04-3 the following in syslog: Oct 14 09:51:00 ThinkCentre-M92p org.gtk.vfs.Daemon[1646]: ** (gvfsd:1725): WARNING **: dbus_mount_reply: Error from org.gtk.vfs.Mountable.mount(): Failed to mount Windows share: Invalid argument
Oct 14 09:54:42 ThinkCentre-M92p org.gtk.vfs.Daemon[1646]: message repeated 3 times: [ ** (gvfsd:1725): WARNING **: dbus_mount_reply: Error from org.gtk.vfs.Mountable.mount(): Failed to mount Windows share: Invalid argument]

These mean nothing to me but perhaps to someone.

Problem solved — Rebooted NAS and all OK.