I wanted to upgrade my 10.04 PC to 12.04. Towards the end of the upgrade, I made the foolish mistake of thinking "Hibernate" on the system menu meant "Sleep", when it reality it seemed to shut down the computer. When the computer restarted it exploded with the weirdest errors, cumulating in "Plymouth main process (56) killed by SEGV signal".

So since I didn't have any files I cared about on the computer, I decided to go ahead and clean install 12.04. I used unetbootin on my Macbook Air (no CD drive) to install 12.04 via a downloaded DMG, and tried to boot up the computer to start the installation. I ended up with a "Missing operating system" error.

What am I doing wrong? I've read that I need to make the USB drive "bootable", but doesn't unetbootin take care of that? It is a Samsung USB drive, but I've reformatted and wiped it so there's no U3 partition.


The Macbook Air is known to not be able to boot from an USB stick (see 1, 2).

You need to put the live cd on the harddisk as described in 1 or use a special script to make the USB live cd boot on the Macbook Air.


It sounds like the computer isn't trying to boot from the USB drive, instead attempting to boot from the first hard drive. When the system first starts booting, see if there is a key you can press to bring up the boot menu (eg. F10 or F12). If not, go into the BIOS or EFI and tell the system to boot from the USB drive first.

Some systems list the USB drive as another hard drive so you may need to change the order of hard drives so the USB drive is first.

  • The key is F8, and I used it to boot to the USB, and I that's when I got the "Missing Operating system" error. Thanks though. – element119 May 7 '12 at 0:09
  • Sounds like unetbootin might have screwed up somewhere, I'd try recreating the USB. – tgm4883 May 7 '12 at 2:22
  • I did... twice. :P I even tried using the daily from Ubuntu's FTP servers, but to no avail. I'm trying to at least install some version of Ubuntu so I can upgrade when I "get in". – element119 May 7 '12 at 2:27

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