I am trying to make a bootable USB with the dd command since Boot Camp does not work. If I execute this command:

sudo dd if=Win10.iso of=/dev/disk1 bs=1m

I get a disk formatted as Universal Disk Format with a GUID partition scheme making it unbootable. The way I changed it to Master Boot Record (FDisk) partition scheme was to erase the failed USB contents, change it to FDisk, and run the dd command with disk1s1 instead of disk1 (disk1s1 was the identifier of the only partition on the USB).

What that has done was made an unmounted partition called disk1s1, formatted in FAT and with the FDisk partition scheme, but it is unmountable and I cannot boot from it. When I try mounting it, nothing happens, and the terminal command output is Volume on disk1s1 failed to mount. I cannot repair disk and Verify disk says Invalid BS_jmpBoot in boot block: 000000

As far as I can remember, Ubuntu's bootable USB showed similar behavior with the unmountable disk, but it was detectable by rEFInd.


The error message I get in VirtualBox is:

VD: error VERR_NOT_SUPPORTED opening image file '/Users/username/RawWinDisk.vmdk' (VERR_NOT_SUPPORTED).
VD: error VERR_NOT_SUPPORTED opening image file '/Users/username/RawWinDisk.vmdk' (VERR_NOT_SUPPORTED).
Failed to open image '/Users/username/RawWinDisk.vmdk' in read-write mode (VERR_NOT_SUPPORTED).
Failed to attach driver below us! Not supported. (VERR_NOT_SUPPORTED).
AHCI: Failed to attach drive to Port0 (VERR_NOT_SUPPORTED).

I am using OS X 10.9.5 (Mavericks), and I have a 13-inch, Mid 2012 MBP

  • I'm by no means any kind of terminal expert, but does this line help any towards the format? from a script I use to generate MBR SD cards - do shell script "diskutil eraseDisk \"MS-DOS\" " & diskName & " MBRFormat " & BSD_disk
    – Tetsujin
    Commented Oct 4, 2015 at 17:21
  • @Tetsujin What does the line do? Does it erase and format as FAT? When I delete and redo the dd command, it does not stay as FAT, but formats itself into UDF and GUID again.
    – John K
    Commented Oct 4, 2015 at 17:23
  • yes, it makes sure they format as MBR/FAT32 - otherwise they format as GUID/FAT32 which does not work for my end purpose
    – Tetsujin
    Commented Oct 4, 2015 at 17:25
  • What is the reason you cannot use the Boot Camp Assistant? Commented Oct 4, 2015 at 17:25
  • @user3439894 Error message saying "Bootcamp only supports windows 7 or higher" I found a fix with adding my model ID to the plist, but that crashes Bootcamp on launch
    – John K
    Commented Oct 4, 2015 at 17:28

1 Answer 1


Let me know if anything goes wrong! I have tried to update everything for the latest version of VirtualBox, but I may have messed up somewhere...

The method I use relies on VirtualBox for its operation. Follow these steps:

  1. Install the latest version of VirtualBox from https://www.virtualbox.org/wiki/Downloads. Make sure it installs the command line tools.
  2. Once installed, open it and create a new VM by clicking "New" on the top left.
  3. Select the type to be "Microsoft Windows", and select the version as "Windows 10 (64 bit)", then give it a name of your choosing.
  4. Select "Do not add a virtual hard drive". We will be creating one on our own for our purposes. Click "Create".
  5. If you have not created a partition for Windows, do so now in Disk Utility. Click on the disk (not any partition) in the sidebar, and click the partitions tab. Then click the "+" button, and make a new partition as large as you want it to be. 30GB is a good minimum size.
  6. Now we have to open the Terminal. Type the following command: diskutil list. From the list of disks, make a note of the disk identifier in the last column that belongs to the partition you created for Windows. We will need this in the next step.
  7. Run the command sudo chown $USER /dev/disk#s#. Replace disk#s# with the identifier from earlier. Enter your password and push return. Also run sudo chown $USER /dev/disk#s1. Use the same identifier, but replace the last number with a 1. Also run sudo chown $USER /dev/disk# using the first half of your identifier (minus the s# part).
  8. Unmount the disk by typing diskutil unmount /dev/disk#s# using your identifier.
  9. Now we have to create the disk for the VM to use for installation. Run the command VBoxManage internalcommands createrawvmdk -filename ~/RawWinDisk.vmdk -rawdisk /dev/disk# -partitions 1,#. Replace "disk#" with the appropriate first half of the identifier from earlier, and replace the second # sign with the last number in your identifier.
  10. Unmount the disk again diskutil unmount /dev/disk#s#, using your identifier.
  11. Now you should have a ".vmdk" file in your home folder. Go back into VirtualBox, select the VM you created, and click "Settings". Select the "Storage" tab, add an IDE controller by clicking the second "+" icon at the bottom, click on the "IDE" controller and click the second "+" sign directly to right of the controller (the hover text is "Add Hard Disk").
  12. Click "Choose existing disk", and navigate to the VMDK we just created, which should be in your home folder. Click it and select "Open". Now you should see the newly added disk just below the "IDE" controller.
  13. Click on "Empty" just below the "SATA" controller, check "Live CD/DVD", and click the little CD icon next to "SATA Port #".
  14. Click "Choose Virtual Optical Disk File...", navigate to your ISO, and open it.
  15. Start the VM and install windows on the 30G partition.
  16. When the installation is done and you're logged in, shut down Windows and you should see the disk created by Windows appear on the desktop. You can get the Boot Camp drivers for your laptop from https://support.apple.com/kb/DL1720?locale=en_US. Put this on a flash drive formatted as ExFAT or FAT so Windows can read it.
  17. You should now be able to reboot into Windows by holding alt down, or selecting the disk in Startup Disk preferences.

Make sure you update your BootCamp with Apple Software Update once you have BootCamp installed on the Windows side. These are technically Windows 8.1 drivers, which should work well enough for you to at least connect to the internet and get the latest version.

  • Thanks. It doesn't look like a hard to follow method as you said. I am trying it now :)
    – John K
    Commented Oct 4, 2015 at 18:12
  • I get the error result code NS_ERROR_FAILURE (0x80004005), and a recurring VERR_NOT_SUPPORTED
    – John K
    Commented Oct 4, 2015 at 18:37
  • At which step ? Commented Oct 4, 2015 at 18:38
  • Upon starting the virtual machine. Also, there is a RawWinDisk and a RawWinDisk-pt. I used the one without pt imgur.com/bTf7IRD . I'll try re-installing VirtualBox
    – John K
    Commented Oct 4, 2015 at 18:42
  • 1
    Actually, VERR just means VirtualBox Error. Commented Oct 4, 2015 at 18:54

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