Comment 19 for bug 1727653

The backup completed succesfully (while running automatically) after I changed in /etc/xdg/autostart/org.gnome.DejaDup.Monitor.desktop from

Exec=sh -c "ulimit -v 1000000; exec /usr/lib/x86_64-linux-gnu/deja-dup/deja-dup-monitor"

to

Exec=sh -c "ulimit -v 1000000; ulimit -n 4096; exec /usr/lib/x86_64-linux-gnu/deja-dup/deja-dup-monitor"

Limits file of process under /proc still shows
Max open files 1024 1048576 files