### Make a bootable Windows USB from Linux

Ubuntu has already an application called Startup Disk Creator, but this can only be used to make Linux bootable USB drives. To make a Windows bootable USB there is an application called WinUSB but it hasn't been updated for a while.
The following guide has been updated and works on any Linux distribution as long as it has GRUB and GParted installed and can make bootable USB for any Windows version newer than Vista: Windows Vista, Windows 7, Windows 8, Windows 8.1 and Windows 10. UEFI boot is only supported for Windows 7 x64 and newer.
Before starting, let's mention that there are two types of boot methods. There is the MBR code type where the bootable executable is stored in a reserved section at the beginning of the storage device. And there is the EFI type, where the boot loader executable file is stored at a standard path in an FAT32 filesystem.
You must decide in advance what you will use. There are some variables for each boot type. If you have no idea what to use, the most common setup that works with unmodified Windows sources, is msdos partition table with fat32 filesystem and flag the partition with boot. In this way you will get both an MBR and UEFI bootable drive.
Partition table Filesystem Partition flag
MBR bootable msdos ntfs / fat32 boot
UEFI bootable msdos / gpt fat32 boot / msftdata *
* msdos should be flagged with boot and gpt should be flagged with msftdata.
UEFI can only boot FAT32 drives! If you need to make an NTFS UEFI bootable flashdrive to remove the 4 GB maximum file size restriction of FAT32 see this: UEFI NTFS: Bootable Windows USB from Linux.

If you prefer, here is the video version of what is about to follow:

## 1. Format USB drive

This is the first step. GParted has a nice GUI and it is easy to use for this. So, plug in your USB flashdrive and start GParted (root permissions required). Select the USB drive and unmount it, otherwise you won't be able to format it.
Warning! Selecting the wrong device will result in data loss!

GParted main window. The first thing to do is select the USB drive.
Right-click the USB drive partition and select Unmount
You must re-create the partition table by going to the Device menu then select Create Partition Table. Choose msdos (or gpt if you want an UEFI only bootable drive) and click Apply.

The Partition Table dialog.
Right click the unallocated space and select New. Make a primary NTFS or FAT32 partition and give it a label too. The label must be as strange as possible because the bootloader will identify the bootable partition by this and you should not use windows like I did in the video! If the filesystem is FAT32 use only uppercase letters. For example: WUSB1840 would be a good label (W for Windows, USB for USB flash drive and 18:40 is the time I was writing this). Remember the label as you will need it later.
If you have a customized Windows with install.wim larger than 4 GB you should definitely go for NTFS. Otherwise, if you choose FAT32, you could get the flashdrive bootable from UEFI too.

New partition dialog
Apply all pending operation from Edit menu - Apply all operations or click the button on the main window.
Right click the partition and choose Manage flags. If you chose the msdos partition table tick boot. If you chose the gpt partition table, msftdata should already be checked.
The Apply button from the main window of GParted

## 2. Copy Windows files

Quit GParted and use the file manager to copy all files from Windows ISO to USB stick. Mount the ISO using Open with - Disk Image Mounter (if you use Nautilus as a file manager). If that fails you can use Furius ISO Mount and loop-mount the ISO.
Select all files Ctrl+A and Copy to USB drive which will be automatically mounted when you click on it at /media/<username>/<drive_label>.
After the copy process is finished, look in the USB root folder for the boot directory. If it is uppercase, rename it to lowercase.

## 3. Make it bootable

If you used NTFS filesystem and MSDOS table, only method A is available. If you used FAT32 and MSDOS table, you can apply method A, B or both. If you used GPT partition table, only method B should be followed.

### A. MBR bootable

GRUB will be used for that. Open a Terminal and run:
sudo grub-install --target=i386-pc --boot-directory="/media/<username>/<drive_label>/boot" /dev/sdX
Replace:
• /media/<username>/<drive_label> with the path where USB drive is mounted;
• /dev/sdX with the USB drive, not the partition (e.g. /dev/sdb)
Warning! Selecting the wrong device (/dev/sdX) may result in bootloader corruption of the running operating system!
Wait for it to finish. If everything is OK, you should see:
Installing for i386-pc platform.
Installation finished. No error reported.
Now, create a text file and write the following in it:
default=1
timeout=15
color_normal=light-cyan/dark-gray

insmod ntfs
insmod search_label
search --no-floppy --set=root --label <USB_drive_label> --hint hd0,msdos1
ntldr /bootmgr
boot
}

menuentry "Boot from the first hard drive" {
insmod ntfs
insmod chain
insmod part_msdos
insmod part_gpt
set root=(hd1)
boot
}
Replace <USB_drive_label> with the label from step 1 (you can place it between quotes if it contains a space, although it is not recommended to use spaces in drive label). Save the file as grub.cfg and put it on the USB drive in the boot/grub folder.
That's it. The USB drive is now bootable from BIOS and can be used to install Windows on your PC. The first time you boot from it in MBR BIOS or CSM mode select Start Windows Installation.

### B. UEFI bootable

Not all Windows versions are supported. Windows 7 on 64 bits, Windows 8 and newer versions should work.
After the copy process is finished, look in the USB root folder for the efi/boot directory. If there's a bootx64.efi or bootia32.efi file there, then you're done. You can boot from your USB in UEFI mode.
If the OS you are making a bootable USB for is Windows 7, browse the efi/microsoft folder and copy the entire boot folder from this path one level up in the efi folder. Merge folders if boot already exists.
Here is what to do if you don't have the bootx64.efi file in efi/boot folder. Browse the mounted Windows ISO image into the sources folder. Open install.wim (or install.esd) with your archive manager (you will need 7z installed). Go to the path ./1/Windows/Boot/EFI and extract the file bootmgfw.efi anywhere you want. Rename it to bootx64.efi and put it on the USB drive, in the efi/boot folder. If you can't find bootmgfw.efi in install.wim then you probably have a 32 bit Windows ISO or other types of images (recovery disks, upgrade versions).
You can now boot from your USB in UEFI mode.

## Errors

1. modinfo.sh doesn't exist
grub-install: error: /usr/lib/grub/i386-pc/modinfo.sh doesn't exist. Please specify --target or --directory.
Install the grub-pc-bin package with sudo apt install grub-pc-bin and run the grub-install command again.
2. Embedding errors
If you get embedding errors (something like filesystem 'x' does not support embedding or Embedding is not possible), be sure you are installing GRUB to USB device and not USB partition. Most likely you typed /dev/sdb1 instead of /dev/sdb (sdb is just an example here). If it still doesn't work, try zeroing the USB drive (at least some sectors at beggining) or use a different USB flash drive.
3. Blocklists
Sometimes, GRUB will not want to install on some flash drives. Try to force it by adding --force argument to the grub-install command.
4. Alternate root partition selection
The root partition selection may fail if your USB flash drive partition has the same label as one of the partitions on the target computer. The best way of setting the root partition is by UUID.
Launch again GParted and select the USB flashdrive. Right click the partition and select Information. Note the UUID field.

Partition UUID
In grub.cfg, replace the line:
search --no-floppy --set=root --label <USB_drive_label> --hint hd0,msdos1
with:
insmod search_fs_uuid
search --no-floppy --fs-uuid --set root <drive_UUID>
where you will replace <drive_UUID> with the UUID you got from GParted.
Still getting errors? If you want an useful answer, please post a comment with the complete grub-install command and the error message.

1. Amazing! I used Etcher and it didn't work, but with your steps it was extremely straightforward. Thanks!

2. Thanks for your tutorial, after so many reattempts, finally got clear instructions.

3. Prasanth MadhurapantulaMarch 7, 2018 at 7:16 PM

Great Tutorial! Thank You. For people who want to install Windows 7 on a PC that came with Windows 8 or 10 change the BIOS Settings to allow the installation of older Operating Systems.

1. Grub can't find bootmgr in the root of the USB drive. Have you copied Windows files correctly?

5. I try to install a bootable windows 7 install usb from my live knoppix 8.1

Grub doesn't offer the "target" and "boot-directory" options, the knoppix install only supports i386 though and has the option "root-directory"

Running the altered code i get following error:

sudo grub-install --root-directory="/media/sdc1" /dev/sdc

Unknown partition table signature
Unknown partition table signature
Unknown partition table signature
Unknown partition table signature
Unknown partition table signature
The file /media/sdc1/boot/grub/stage1 not read correctly.

I hope you can help me out here.

1. I once tried this from a live Ubuntu. It gave me some errors too. I don't think this works from live medium.

6. I followed the steps and got "Installing for i386-pc platform.
Installation finished. No error reported." at the last step.But when I boot using the flash drive I get a grub command line instead of the "Start Windows Installation"

1. GRUB doesn't find the grub.cfg file or it has incorrect syntax. Check if the file is placed in the right folder and if its name is written correctly (some copied "grub.cfg " - with a space at the end - and had similar issues).

2. I have tried this but still get the grub command line.

When I copied over the iso contents there was no "grub" folder within "boot" so I made one, and then placed the "grub.cfg" file inside it but to no avail. I also copied the file into the "boot" folder and tried, but no luck there either

3. The grub folder appears after you run grub-install.

7. I have gotten past the empty grub menu but now I juat get a blank screen when it loads. I have tried this with both a windows 7 and 10 install but get the same problem

8. I followed all of the instructions and got no errors, but it just boots to a black screen and nothing happens. Bad ISO?

9. Works like a charm. Thank you so much.

10. Dude ! Thatnk a lot !! I struggled a lot but finally found solution here ! And itsi working

11. Bless you, sir. Bless you

12. I got a black screen with a flashing underscore :(

1. Try with a different USB drive.

13. I've tried the usual stuff with dd and cp, which works for every Linux and also worked with windows years ago. But now only this method seems to work, so many thanks!

I may suggest, just to help you no offense meant, to design this blogpost more clear. It is very complete and covers almost all possibilities, but usually one is not looking for that. You even handle 32 bit for every step. Its a lot to read between the parts that i was interested in, which was basically:

1. Format your drive msdos and create a fat32 partition.

your step 3 wasnt neccessary at all. May explain how formatting is done on demand though, though folding text e.g.

1. Thank you for feedback!

14. i am getting error while installing as

i am trying to install win 10 on a legacy boot pc which only had windows 7 before .

can you help

15. Thank you, it saved my day

16. Thank you,Thank you,Thank you, you saved my day

17. Hi, the grub-install seems to be failing...any idea of the error below:

grub-install: warning: File system `ntfs' doesn't support embedding.
grub-install: warning: Embedding is not possible. GRUB can only be installed in this setup by using blocklists. However, blocklists are UNRELIABLE and their use is discouraged..
grub-install: error: will not proceed with blocklists.

1. "You are getting the warning because you are installing grub to a partition instead of the MBR. This means grub can not be embedded in the unused space between the MBR and the first partition." See https://unix.stackexchange.com/questions/174206/warning-file-system-ext2-doesnt-support-embedding-but-my-system-isnt-emb.

18. For anyone who is having an error "install.wim file too large" you need to split the install.wim file in the sources folder from the disk image. For linux users, install wimtools and use wimsplit from the terminal.

19. nice writeup!

20. My boots back into linux mint on selecting the usb help pls

1. Probably, your USB drive is not bootable.

21. Thanks man! it worked nicely!

22. I just can't put the changed bootx64.efi file back onto the boot usb stick since it thinks it's a CD_ROM. Would there be any chance for help for me?

1. Mount the USB drive from terminal (see this).