(gtk_accel_path "<Actions>/ShellActions/Up" "BackSpace") to ~/.config/nautilus/accels works for me
see https://bugs.launchpad.net/ubuntu/+source/nautilus/+bug/1108637
(gtk_accel_path "<Actions> /ShellActions/ Up" "BackSpace") nautilus/ accels
to ~/.config/
works for me
see https:/ /bugs.launchpad .net/ubuntu/ +source/ nautilus/ +bug/1108637