I have Ubuntu 14.10 with WinUSB and I have a Windows 8.1 Pro ISO with a 4GB SD Card with an empty FAT32 partition. Everytime I try to use it, it says "Installation failed, exit code: 256". How do I fix this?
For some reason winusb kept hanging up on formatting the USB drive, said it couldn't access the drive. I ended up formatting to NTFS using the "Disks" application in Ubuntu and then using
winusb from the terminal:
sudo winusb -v --install Win_7_Pro.iso /dev/sdc
NOTE: you can check to see what your usb device is using
lsblk from a terminal, mine was sdc.
I faced the same error, and tried too many fixes until found the fix. Here is the fix in my case (I hope it works for you too):
open GParted app then
unmountthe USB stick.
open WinUSB or WoeUSB (a fork of WinUSB) and choose the
.isoWindows file, and choose the USB stick. Everything goes right!
If you need to see the fix visually, I made a video on YouTube for the fix.
I just dealt with the same problem... Maybe it will help somebody:
I was getting this error when I clicked TARGET DEVICE and INSTALL, but if you click OPTIONS and SHOW ALL DEVICES and then you select your TARGET USB drive, it works... or at least it did in my case.
Of course my drive was formatted as NTFS!
EDIT: At the end of process error appeared, but Windows installation booted just fine.
If the Win8.1 is 64bit I understood (reading results from a Google Search) that you need at least 8GBs.
And obviously NTFS, not FAT. Indeed, I quote an excerpt From the help:
$ winusb --help winusb usage Install a windows ISO on an NTFS partition and edit MBR of the device [...]
And from the CLI you can also ask for the verbose mode, maybe you can have more informations on the error.