Comment 5 for bug 1715582

today the update of deja-dup came in (35.6-0ubuntu1 -> 36.0-0ubuntu1)

There is no directory /var/cache/samba which the application searches for.

creating it, does not help ->
Backup failed
Operation not supported by backend

$ deja-dup

(org.gnome.DejaDup:5945): Gtk-WARNING **: Allocating size to AssistantBackup 0x55b7940d0d70 without calling gtk_widget_get_preferred_width/height(). How does the code know the size to allocate?

** (org.gnome.DejaDup:5945): WARNING **: BackendRemote.vala:83: Could not find enclosing mount

** (org.gnome.DejaDup:5945): WARNING **: BackendRemote.vala:83: Could not find enclosing mount

starting deja-dup with sudo rights ->
Backup failed
volume doesn’t implement mount

on the console deja-dup complains that it cannot find /var/cache/smb:
$ sudo deja-dup

** (org.gnome.DejaDup:5846): CRITICAL **: string_contains: assertion 'self != NULL' failed

(org.gnome.DejaDup:5846): Gtk-WARNING **: Allocating size to AssistantBackup 0x5609b7db2070 without calling gtk_widget_get_preferred_width/height(). How does the code know the size to allocate?
gpg: WARNING: unsafe ownership on homedir '/home/wolf/.gnupg'

** (org.gnome.DejaDup:5846): WARNING **: BackendRemote.vala:83: Containing mount for file /var/cache/smb:/s4 not found

mounting the backup volume ->
Backup failed
volume doesn’t implement mount

$ sudo deja-dup

** (org.gnome.DejaDup:5987): CRITICAL **: string_contains: assertion 'self != NULL' failed

(org.gnome.DejaDup:5987): Gtk-WARNING **: Allocating size to AssistantBackup 0x55f188b7f450 without calling gtk_widget_get_preferred_width/height(). How does the code know the size to allocate?
gpg: WARNING: unsafe ownership on homedir '/home/wolf/.gnupg'

** (org.gnome.DejaDup:5987): WARNING **: BackendRemote.vala:83: Containing mount for file /var/cache/smb:/s4 not found

creating /var/cache/smb ->
Backup failed
volume doesn’t implement mount

$ sudo mkdir smb
wolf@mbpr13b:/var/cache$ sudo deja-dup

** (org.gnome.DejaDup:6045): CRITICAL **: string_contains: assertion 'self != NULL' failed

(org.gnome.DejaDup:6045): Gtk-WARNING **: Allocating size to AssistantBackup 0x558b0333f3a0 without calling gtk_widget_get_preferred_width/height(). How does the code know the size to allocate?
gpg: WARNING: unsafe ownership on homedir '/home/wolf/.gnupg'

** (org.gnome.DejaDup:6045): WARNING **: BackendRemote.vala:83: Containing mount for file /var/cache/smb:/s4 not found

Even giving o+w does not help

This can be tested on a plain 17.10 installation