I want to upgrade my current O.S. Ubuntu 13.04 to Ubuntu 13.10. For that purpose I created bootable usb stick using
unetbootin. When the laptop boots, it boots from the usb. Now after a few steps there comes options as how to install. Here there isn't the option for upgrading ubuntu which is supposed to be there as clear from this installation manual of Ubuntu. For your ease I'm showing the options as mentioned in the manual below.
Please see the image below that shows what I get when my usb stick boots. It's not having the option for upgrading. ( Also its not having the option for erasing the current O.S. Rather it has option for erasing the whole disk!!! Because of this I can't replace the current Ubuntu 13.04 with 13.10. )
It may happen that the problem won't be resolved using usb stick. Then tomorrow I will purchase DVD and burn the Ubuntu 13.10 iso image there. DVD should work as earlier also when usb stick didn't work to install my Ubuntu 12.10 then DVD worked perfectly.
Also I would like to add how I prepared my usb stick. Using
fdisk, I deleted the partition there. I Created only 1 new partition to occupy whole 2GB of space of my usb stick or flash drive whatever you say. Then using
mkfs created file system of ext4 type. Then using
unetbootin created bootable ubuntu 13.10 from its iso.
I have a related thread here.