Install iso to flash drive

Check with md5sum that the download was successful. See this link: UbuntuHashes

Try with mkusb according to this link. It uses the cloning method to install from iso files (and other image files) to flash drives (and other mass storage devices). The cloning method is very reliable.

https://help.ubuntu.com/community/mkusb

The fastest way to start making USB boot drives is to install the mkusb PPA, install and update the mkusb package like all the other program packages.

If you run standard Ubuntu, you need an extra instruction to get the repository Universe. (Kubuntu, Lubuntu ... Xubuntu have the repository Universe activated automatically.)

sudo add-apt-repository universe  # only for standard Ubuntu

sudo add-apt-repository ppa:mkusb/ppa  # and press Enter
sudo apt-get update
sudo apt-get install mkusb

Edit: If you install from ubuntu-mate-16.04-desktop-amd64, you can use usb-creator-gtk version 0.3.2, which comes with 16.04. But if you install from a previous version, it is better to use mkusb, which works in all current versions of Ubuntu and Ubuntu flavours (including 12.04, 14.04, 15.10, 16.04 and Yakkety Yak).

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