When you installed davfs2 it should have created the group, so I think the issue is your not a member of the group
sudo adduser username davfs2
Then log out and in again.
Edit
So it seems they have made some changes on their end. This is how I was able to get it setup and working
sudo apt-get install davfs2
Then create a mount point
sudo mkdir /media/user@box.com
Here is where the difference is
To mount the drive you need to run the command
sudo mount -t davfs https://dav.box.com /media/user@box.com
It will then prompt you for your username and then your password
You should now be mounted.
You can verify this by the fact that you receive no error message and if you run
df -h
you should see
https://dav.box.com 10G 0 10G 0% /media/user@box.com
Edit 2
Don't forget to chown the mount point to user, otherwise you will need to use sudo. Substitute user:user with your own Ubuntu username
sudo chown -R user:user /media/user@box.com
I got an error
chown: changing ownership of ‘user@box.com/lost+found’: Invalid argument
but it did change ownership of user@box.com as well as user@box.com/dav (the upload directory)
Edit 3
Just in case you need. You can add your password to secrets file so don't need to enter all the time. Plus this will also make it easier to auto mount with fstab.
sudo nano /etc/davfs/secrets
add the following to the end of the file
https://dav.box.com/dav username password
Now if you want the drive auto mounted at startup (I'm sure you do) you just need to add the following to
sudo nano /etc/fstab
https://dav.box.com/dav /media/user@box.com davfs _netdev,rw,user 0 0
If you still have the drive mounted go ahead and unmount it by using
sudo umount /media/user@box.com
Now you can verify that the mount will auto mount at start by running
sudo mount -a
and then
df -h
to verify you see
https://dav.box.com/dav 10G 0 10G 0% /media/user@box.com
If this works for you, please be sure to mark the answer as accepted so we both get credit and more importantly, so the next person that comes along knows it's a working solution.
Best Answer
After debugging was turned on using
DEJA_DUP_DEBUG=1 deja-dup --backup > dejadup.log 2>&1
, your dejadup.log file contains:and a bit further:
So the error must be on the davfs side and you should investigate the server as locally there is nothing wrong at all.