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I've just created a multiboot USB stick using Yumi. I tried to start my notebook (Asus K70IO) using it, but all I see is just a black screen with blinking underscore even after waiting for minutes. If during this time I remove the USB stick I get the message: "Operating system load error".

How do I properly load my Yumi USB stick and use it? I've tried formatting it using Yumi's checkbox to format the stick in FAT32 too, but it didn't help.

Now I tried to use Sardu 2.0.5 and met same problem: black screen and blinkin underscore, if I remove stick I see "Operating system load error" and my OS starts to boot.

At the same time if I create bootable USB stick from ISO using UltraISO it boots smoothly.

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migrated from Sep 12 '12 at 18:28

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I'm steal searching for a fix, but don't have any idea yet. – Andrew Nikolin Sep 27 '12 at 14:57
One thing I noticed, the drive seems to need to be formatted to FAT32, I had mine as exFAT and it wouldn't make it bootable. Just check the "Format drive" and that might fix it. – Ben Mar 15 '15 at 4:18

I know its a couple years late, but here goes....

It can be a factor of factory formatting. Many USB sticks are formatted USB-FDD (Floppy disk) when what you really need is USB-HDD. Windows inherently formats USB drives as FDD for which it will not write to MBR. But with a specific command line called DISKPART you can wipe the disk and set it up as a USB-HDD with an appropriate MBR. Here are some pretty simple steps, take caution though, one small misstep could send to "no-reboot land":

  1. Run Comand Prompt as Admin and use the following commands:
  3. LIST DISK - find the disk number of the usb drive
  5. CLEAN
  6. ACTIVE - Make the drive active
  7. FORMAT FS=FAT32 - fat16/32 are the best option for syslinux
  9. EXIT

This should get you ready to go unless the USB drive is truly the culprit. This just fixed the exact SAME problem I was having with YUMI.

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Someone wrote in a (now deleted) "answer" that for them Clean was not needed, and that the order should be Format, Assign, Active or Format, Active, Assign. (I've no idea if that is true.) – Arjan Oct 25 '15 at 12:38
So I thought YUMI would make UEFI disks, not disks with MBR partitions. Is there a way to make it write UEFI disks? – Gui Imamura Dec 11 '15 at 13:55
up vote 2 down vote accepted

So the problem is solved. Seems that something was wrong with 2 USB sticks(Kingston DT 100 G2 and Spaceloop XL), because when I made bootable USB with third stick - it started without any problems. But still, I can't understand why these sticks weren't working.

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See the other answer – Gui Imamura Dec 11 '15 at 13:57

Yumi works very well and I don't think it's the problem. It's most likely the USB that your using. Some brands of USB's don't work well with the Yumi for some reason. I don't know why but I recently had a problem with Verico Evolution MK II USB. It just didn't work with Yumi at all.

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