This is because

1) check any update is available then finish it
2) go to application manager and install linux kernel
and after that not install nokia kernel
3) go to terminal type root and
type mount -t usbfs usbfs /proc/bus/usb
if the above command is not working then type
mount -t usbfs usbfs /dev/bus/usb

If the above things are successfully completed then you can flash without any problem

Thank You