Why can Déjà Dup not complete the backup of .cache/dconf and .gvfs?

I've been able to solve my question after finding this web page. You need to update the owner and group for each file which is failing to backup. I used these commands to solve the situation.

sudo chown mjwittering .cache/dconf .gvfs
sudo chgrp mjwittering .cache/dconf .gvfs

Then run the backup again, which should now complete successfully.