How not to get a "missing operation system" error when booting the system from a flash drive?

Question

ISO

Now I tried to burn the image ubuntu-12.04.4-desktop-amd64.iso
using unetbootin and startup disk creator on ubuntu 14.04.
Why is some kind of clumsy bootloader written on the flash drive and how to fix it?
Tell me what am I doing wrong?
upd: issue resolved. I'll write a similar question here, let it be indexed. How to burn a flash drive on Linux / Ubuntu?

Answer 1

Startup disk creator out of the box should record everything normally ( bootmgr bootloader ).
Use dd:
Instead of sdb, your device.