Tech Tip: How to Use Boot Camp on an External Drive

Boot Camp IconBoot Camp and Boot Camp Assistant allow you to install Windows on your Mac. It’s a nice capability that lets you select – at boot time – which operating system you wish to use: macOS or Windows.

One of the downsides to Boot Camp and the Windows installer is that it restricts you to installing Windows on your Mac’s internal drive. While Boot Camp Assistant can partition your startup drive for you to make room for Windows, there are bound to be many of you who just don’t have room to spare on your startup drive to install Windows.

Installing Windows on an external drive would be a great solution to the problem of available space, but as we said, Boot Camp and Windows impose a restriction on installing to an external drive – or do they?

There are actually a few ways you can successfully install Windows on an external drive. They range from creating clones of an existing PC installation or using Microsoft IT tools for installing Windows. But the method we’re going to outline here is a bit different. It allows you to install Windows on an external drive without first having Windows installed on a PC or in a virtual environment.

This is an advanced process with quite a few pitfalls that can trip you up. Be sure to read through the process before undertaking it. Also, make sure you have a current backup before beginning.

What You Need

  • 4 GB or larger USB flash drive.
  • Bootable external drive. We’re using a USB 3.0 drive, but a Thunderbolt drive should work as well.
  • Boot Camp Windows Support Software.
  • VirtualBox virtualization app (available for free).
  • A licensed copy of Windows 10 ISO or an install DVD.
  • Wired keyboard and mouse. During the Windows installation, the drivers for Apple wireless keyboards and mice aren’t installed until the very end of the process. If you’re not using a portable Mac with a built-in keyboard and trackpad, you’ll need a wired keyboard and mouse to complete the installation.

Prepare the External Drive for Installing Windows
The external drive that you’ll install Windows on needs to be prepared by erasing and formatting the drive for use with Windows.

Warning: The erase, format, and partitioning process will delete all data currently contained on the external drive.

1) Ensure the external drive is connected to your Mac.
2) Launch Disk Utility, located at /Applications/Utilities.
3) In the Disk Utility sidebar, select the external drive that will be used for Windows. The device will likely have the name of the external enclosure’s manufacturer listed. Do not select the volume located just underneath the device name.
4) Click the Erase button in the Disk Utility toolbar.
5) Use the dropdown menu to set the Scheme to “Master Boot Record.”
6) Use the dropdown menu to set the Format to “MS-DOS (FAT).”
7) You can use any name you wish (up to 8 characters), but we suggest naming the external WIN10.
8) Click the Erase button.

The external drive will be formatted and a single MS-DOS (FAT) volume will be created.

Prepare the USB Flash Drive for the Windows Support Software
The USB flash drive needs to be formatted to accept the Windows software that Boot Camp Assistant will download and install.

(The flash drive needs to be formatted for use on Windows.)

Warning: The process of preparing the USB flash drive will delete any data contained on the flash drive.

1) Make sure the USB flash drive is connected to your Mac.
2) Launch Disk Utility, located at /Applications/Utilities.
3) In the Disk Utility sidebar, select the USB flash drive device. The device will likely have the name of the USB flash drive manufacturer listed. Do not select the volume located just underneath the device name.
4) Click the Erase button in the Disk Utility toolbar.
5) Use the dropdown menu to set the Scheme to “Master Boot Record.”
6) Use the dropdown menu to set the Format to “MS-DOS (FAT).”
7) You can leave the Name field as is.
8) Click the Erase button.

The USB flash drive will be formatted and a single MS-DOS (FAT) volume will be created.

Download Boot Camp Windows Drivers
We only need Boot Camp Assistant for its ability to download all of the Windows drivers we’ll need to ensure the install of Windows will run correctly on Mac hardware. We won’t be using Boot Camp Assistant to partition a drive or step us through the install process.

(The latest version of the Apple drivers that Boot Camp needs can be downloaded using Boot Camp Assistant.)

1) Launch Boot Camp Assistant, located at /Applications/Utilities.
2) In the Boot Camp Assistant window that opens, click the Continue button.
3) In the Select Tasks window, remove checkmarks from “Create a Windows 7 or later version install disk” and “Install Windows 7 or later version.” Make sure the checkbox labeled “Download the latest Windows support software from Apple” is checked, and then click Continue.
4) Select the device you wish to have the Windows support files installed on; this should be the USB flash drive you prepared earlier. After making your selection, click Continue.
5) Boot Camp Assistant will download and install the needed Windows support software on the selected device.
6) Once the install is nearly complete, you’ll be asked to provide your administrator password so the Boot Camp Assistant can change the file permissions on the USB flash drive. Provide your administrator password, and click Continue.

The Windows support software has been installed on the USB flash drive.

Use VirtualBox to Install Windows on the External Drive
This is the tricky part of the process, at least in the sense that we’re going to trick Boot Camp and the Windows installer into thinking your external drive is actually your main internal drive, or in the parlance of Windows, your C: drive.

You could perform this tricky bit of virtualization using Parallels or VMware Fusion, but we’re going to use VirtualBox because it’s free. You can download the app from the VirtualBox website.

Once you download and install VirtualBox, we’re ready to begin the installation process.

Most of the virtualization trickery will be performed from within Terminal, so go ahead and launch Terminal, located at /Applications/Utilities.

(You can find the external drive by looking for the name, type, or if this is your only external, by the location [external, physical]).

1) With the external drive that you formatted for installing Windows on connected to your Mac, enter the following Terminal command without the quotation marks: “diskutil list” and then press enter or return.
2) A list of all attached disks will be displayed in Terminal. Scroll through the list and locate the external drive you plan on using to install Windows. If you followed our suggestion earlier, it will be named WIN10, and will be of the type DOS_FAT_32.
3) Once you locate the external drive, make a note of its Identifier. The Identifier appears in the last column and will have the format of the word “disk” followed by a number. In our case, the identifier is disk4.
4) Now that we know the disk identifier, we need to eject the disk so it’s no longer connected logically to the Mac (it will still be connected physically).
5) Locate the WIN10 disk on your Desktop or in the Finder window sidebar.
6) Right-click on the WIN10 disk and select Eject from the popup menu.

Use VirtualBox to Map the External Drive to a VirtualBox Disk
The next step in the process is to map the external drive to a VirtualBox disk.

1) In Terminal, enter the following without the quotation marks: “sudo VBoxManage internalcommands createrawvmdk -filename “bootcamp.vmdk” -rawdisk /dev/disk4″ Note: Be sure to replace /dev/disk4 with the actual disk number you found from the disk identifier, and then press enter or return.
2) At the Terminal prompt, enter your administrator password, and then press enter or return.

The bootcamp.vmdk virtual disk will be created in your home folder.

Create a VirtualBox Virtual Machine for Windows
We will use VirtualBox to install Windows 10 to our external drive. We can do this because in the previous step, we mapped the external drive to a VirtualBox virtualized disk.

(The Windows VM you create uses a virtualized connection to your external drive.)

In order for VirtualBox to be able to access the external drive, we need to launch VirtualBox with elevated permissions. Once again, we turn to Terminal.

1) Enter the following at the Terminal prompt without the quotation marks: “sudo /Applications/” Press enter or return.
2) If asked, supply your administrator password, and then press enter or return.
3) VirtualBox will open.
4) In the VirtualBox window, click on the New button in the toolbar.
5) In the sheet that drops down, enter a Name for the installation; we suggest WIN10.
6) Set the Type to Microsoft Windows.
7) Set the Version to Windows 10 (64-bit).
8) Click the Continue button.
9) Accept the default memory size, and click Continue.
10) In the Hard Disk sheet, select Use an existing virtual hard disk file.
11) Just below the option to use an existing virtual hard disk file is a dropdown menu for selecting a file to use. You may notice the menu is empty or does not contain the virtual disk file we created earlier. Click the folder icon just to the right of the dropdown menu. This will allow you to browse to the bootcamp.vmdk file, which is located in your home folder. Select the bootcamp.vmdk file, click the Open button and then click the Create button.
12) VirtualBox has created a virtual environment for us to install Windows 10 in that will actually perform the install on the external drive. The next step is to mount the Windows 10 ISO you downloaded earlier from Microsoft.
13) In VirtualBox, select the Windows 10 virtual machine, and then locate the Optical Drive. This is usually located in the Storage section of the virtual machine. Click the Optical Drive item and select Choose Disk Image.
14) Browse to where you downloaded the Windows 10 ISO.
15) Select the Windows 10 ISO, then click open.

Install Windows on Your External Drive Via VirtualBox
1) Start the installation process by clicking the Start button in the VirtualBox toolbox.
2) The Windows 10 installation will start. Follow the onscreen instructions until you come to the Windows Setup screen with the heading “Which type of installation do you want?”
3) Select the “Custom: Install Windows only (advanced)” option.
4) The Windows setup will display the currently available drives and partitions that Windows can be installed on. Because the external hard drive has been assigned to the VirtualBox machine, it is the only drive that will be listed.
5) When we used Disk Utility to format the drive, we chose MS-DOS (FAT), which is incompatible with Windows 10. We did this because Disk Utility can’t format with NTSF, but the Windows installer would recognize MS-DOS. All we need to do now is change the drive’s format to NTSF.
6) Select the drive, and then click the Format button.
7) Wait until the format is complete (the Next button will become available), and then click Next.
8) The Windows installation will start, with files being copied to the external drive.

Warning: Extremely important step follows.

9) When you see the message “Windows needs to restart” immediately shut down the virtual machine by clicking on the red close button on the window. Select “Power off the machine” from the list of options, and then click OK to power off the virtual machine.

(Windows Setup will install the needed files to your external drive. Be sure to prevent Windows Setup from automatically restarting.)

At this point, the Windows installer has copied all the files to the external drive, and has set up a boot environment that you can start your Mac from. Next time you boot from the external drive, Windows will complete the installation process.

Restart Your Mac With the External Windows Drive
1) Close any apps you may have open, then restart your Mac.
2) Hold down the Option key during the restart. This will cause the Mac’s Startup Manager to display a list of drives you can start from. Use the arrow keys on your keyboard to select the Windows drive.
3) Your Mac will boot from the external Windows drive. The bootup process can take a while, so be patient.
4) Windows will finish the install process. At some point during the installation, Windows will restart your Mac. When it does, your Mac will restart with the normal Mac OS. You need to be present to hold down the Option key and select Windows to start from.
5) Windows will finish the installation and present you with the Windows desktop.

Getting Apple Hardware Working Under Windows
The USB flash drive you used earlier to make the Windows Support software contains all the drivers you need to install in Windows for the Apple hardware to work.

(To complete the Windows installation, run the Boot Camp Setup app to install the needed Apple drivers.)

1) Make sure the USB flash drive is connected to your Mac.
2) Click on the Windows Start button and select File Explorer.
3) In the File Explorer sidebar, select the USB flash drive, it will probably have a D or E drive letter assigned to it.
4) Open the Boot Camp folder
5) Run the Setup app inside the Boot Camp folder.
6) Follow the onscreen instructions to install the Boot Camp drivers.

Once the installation completes, all your Apple hardware, including wireless keyboards and mice, should be working.


  • Does this work on the 2018 MB Pro 15” and is it possible to also use the external drive as a storage device or is it only able to have the boot up on it??

  • Sorry: the message is: No bootable disk, isrt boot disk and press any key…

  • ok, have followed your changes, and after installing windows,i reboot (in time) my mac with the alt-key, he shows 2 disks (OS and Windows) , select the windows-disk, and then a message shows up: . Any idea what i did wrong?

  • I have the same issue as Laura. The bootcamp.vmdk file is greyed out and stands also between quotes. Please can you help me?

  • I created the bootcamp.vmdk file in my home folder, but once I eject the external drive and go into VirtualBox and get to the hard disk sheet, I can browse to the bootcamp.vmdk file, but not select it (its greyed out). What I am missing??

  • Amazing reference. Thank you!

    I’ve done my own run of the setup and it works very well. My notes on change required are listed here:

  • So I get all the way up to the installing from the virtual box part. But once I select the ISO for the optical drive and start, I can’t get past the screen where it says “press any key to boot from CD or DVD…”

    Any suggestions?

  • Dude you realize can just download those programs from there respective website instead of using that which i think is a virus because there is no viruses that come with the program that are shown
    so i would stop using that website


  • Hmm, the new versions just give a segfault on VM launch. Don’t know why though.

  • I would love to just buy a drive with Windows 10 on it and ready to be registered!

  • I was able to get it all set up with a combination of tips from comments and the guide. Everything seems to work fine, but I can’t play any videos for some reason. Anybody than can help?

  • I am able to install the windows files onto the external HDD, however, when I try to boot from the drive (after shutting VirtualBox down before Windows is able to restart), I get a blue screen of death every time Windows tries to load, which then makes my computer restart. I’ve tried loading in safe mode, but same problems happens after loading “core files.” I wiped the external HDD and started over with the same outcome. Not sure what is wrong?? Any ideas or help? I’m using a seagate 1TB external HDD.

    • same thing here. did you find any solution?

    • I’m having the same issue running Mojave on my iMac with Windows 10 Home on the external SSD. The BSOD error is DRIVER UNLOADED WITHOUT CANCELLING PENDING OPERATIONS and it happens when Windows is trying to complete setup while booted from the external. I’ve seen a lot of posts over the past week from other bootcamp users experiencing the same issue. Someone speculated that it may be related to the October Windows ISO.

    • I was having the same issue when attempting to install the October release of Windows 10 Home, but found I could successfully install the April release. Windows is running fine now, though I’m not sure what will happen if I attempt to update.

  • Windows10 is successfully running through the VM but when I restart my computer and hold down options the only option I am given is to select the mac startup disk and my wifi network. Any suggestions? Early thanks

  • Hi,

    I did everything listed here and everything worked fine. However when I restarted my macbook and went to the Startup, only my Mac drive showed up. My external hard drive didn’t show up. I re-did everything and I’m still getting the same thing

  • Hi

    Managed to get Win10 all up and running.

    Has anyone else come upon the problem that the April 18 Windows 10 update will not install on an external drive?

    Are there any workarounds to this issue?

    Many thanks

  • Thanks for the great step-by-step. I got this done and it totally works on my WD My Passport Ultra external drive!!

    I’ve gotta say that I got a bit bogged down in the Create a VirtualBox Virtual Machine for Windows section. I had to eject the external drive (remain plugged in) and eject and actually unplug the external drive a bunch of times until I was able create the virtual environment using the bootcamp.vmdk file. In other words, it took several of tries to make the bootcamp.vmdk file populate in the Storage panel in the Virtual Box Manager. I honestly can’t remember if it the external drive was ejected+plugged in or ejected+unplugged when I was successful. I don’t know if this was operator error or just something quirky.

    From then on it was clear sailing. Be sure to heed Tom’s advice on the “Windows needs to restart” bit.

    This is so cool—a way more functional Windows10 on my Macbook Pro than Parallels was.

    Thanks to Tom and Good Luck!

  • Hi.. i did everything right, apparently, got to start windows (7) on my Mac to complete instalation, but it enters an endless loop of restarting, even when I choose “secure mode”… what can I do? or what did I do wrong? Thanks

  • So I have managed to get everything in the installation processes to work up until Windows Setup. During Setup in the “Getting Windows Files Ready” part everything goes smoothly until 10%. At 10% the counter stops going up, the dot for drive activity turns solid red and nothing appears to happen. Does anyone know how to fix this?

  • Hi everyone,

    I’m wondering if I do this, will I later be able to store other things (like photos and videos) on the external hard drive for use from Mac through iPhoto/Photos? Are there additional steps that I will need to take to make this possible?

    Thanks in advance for the help!

  • Hello! Thank you for this awesome tutorial. Also thanks to the comments for the additions.

    I tried it, but unfortunately, whenever I try to start the virtual machine, I get the following error:

    VD: error VERR_RESOURCE_BUSY opening image file ‘/Users/daniel/bootcamp.vmdk’ (VERR_RESOURCE_BUSY).

    Failed to open image ‘/Users/daniel/bootcamp.vmdk’ in read-write mode (VERR_RESOURCE_BUSY).

    AHCI: Failed to attach drive to Port0 (VERR_RESOURCE_BUSY).

    I tried Vince S’ tip and ran “sudo chown MYUSERNAME:staff /dev/disk#”, of course with my username and the right disk identifier.

    Still, I get the same message every time. I also went to my home folder and in the info panel of my vdmk-file set “everyone” to read and write.

    What am I doing wrong? I would really appreciate help.

    Have a good day @ all!

    • Hey Daniel, I got the same errors, make sure the external drive is still unmounted (ejected) when trying to run the virtual machine. Other than that, try restarting your machine and checking to see if there are any flags in the security settings that you need to allow.

      Sorry, I can’t be more specific, I encountered about 3 errors and I can’t remember what fixed what, but those were the things I did

  • I have an issue here.

    I accidentally downloaded the WINDOWS SUPPORT to my desktop and NOT my USB. So, the authentication and verr access wasn’t properly done on the USB.

    This is my fault.

    But, how do I fix it? I went through all the steps, regardless (now I realize, I had done something possibly wrong.)

    This is the error I get when I add the Windows ISO to the virtual disk and I click Start:

    VD: error VERR_NOT_SUPPORTED opening image file ‘/Users/milespauling/bootcamp.vmdk’ (VERR_NOT_SUPPORTED).
    VD: error VERR_ACCESS_DENIED opening image file ‘/Users/milespauling/bootcamp.vmdk’ (VERR_ACCESS_DENIED).
    Failed to open image ‘/Users/milespauling/bootcamp.vmdk’ in read-write mode (VERR_ACCESS_DENIED).
    AHCI: Failed to attach drive to Port0 (VERR_ACCESS_DENIED).

    Is there any terminal commands I can apply quickly to be on my way?

  • I’ve followed every step and it works for me. But with the following additional steps:

    1. Before going to Terminal and map the external drive to the VirtualBox drive, EJECT the external drive first. Or you might have problems creating the bootcamp.vmdk file.

    sudo VBoxManage internalcommands createrawvmdk -filename “bootcamp.vmdk” -rawdisk /dev/disk4

    I typed the above command with quotation marks around bootcamp.vmdk. No problems.

    2. EJECT the external drive again prior to entering the subsequent terminal command to launch VirtualBox. Else you might get an access denied error.

    3. After creating a new VirtualBox drive pointing to the ISO, ensure you enable EFI (for special OSes) for this virtual drive.

    4. After starting the virtual drive, and in the Windows installation screen where you select the drive to install – DELETE the external hard disk (as it was previously set to MBR if you followed the instructions). After that, format the drive and Windows will create a GUID partition automatically for EFI. Then proceed with the installation.

    It should work now if you continue following the steps in the article.

  • Here’s what worked and didn’t work for me.

    I followed the steps up to restarting my mac except:

    1. I removed the quotation mark from this line of code: sudo VBoxManage internalcommands createrawvmdk -filename “bootcamp.vmdk” -rawdisk /dev/disk4 (thanks to the comments for this tip).

    2. I checked the box “Use Host I/O Cache” in VirtualBox. (Thanks to the comments for this tip also).

    3. When I formatted my external drive to NTFS before doing all of the steps, when I got to installing Windows, the installer couldn’t find my drive. When I formatted my external drive to MS-DOS (FAT) the Windows installer didn’t give me an option to format the drive but it still installed.

    4. When I restarted my mac with option pressed down my external drive showed up but when I entered I just got a black screen with a blinking underscore.

    5. Someone also commented that “Enable EFI (special OSes only) should be checked. I tried this but made no difference.

    Thanks everyone for the tips, but unfortunately I couldn’t get it to work. Is there something I’ve missed? Thanks

  • It does not work I keep getting the same error message in Terminal

    VBoxManage: error: VMDK: could not create new file ‘bootcamp.vmdk’
    VBoxManage: error: Error code VERR_ALREADY_EXISTS at /Users/vbox/tinderbox/5.2-mac-rel/src/VBox/Storage/VMDK.cpp(3392) in function int vmdkCreateRawImage(PVMDKIMAGE, const PVDISKRAW, uint64_t)
    VBoxManage: error: Cannot create the raw disk VMDK: VERR_ALREADY_EXISTS
    VBoxManage: error: The raw disk vmdk file was not created

  • I can’t boot the external win10 I made with this guide, through fw.
    I made the installation with usb.
    Is it because the win10 disk is MBR?
    Could this installation be done with GPT disk?

  • Tom,
    Why don’t you just correct the few mistakes in this guide?
    Like “bootcamp.vmdk”.
    And I would add, that you have to eject the WIN10 drive all the time.
    Next time, I’d also use chronological numbering in the steps, so it would be easier to point to them. (Now you have 9 different “step 3” ‘s in the mix…

    Nevertheless, this is the best guide in the web, rufus or wintousb guides didn’t work for me. And I don’t like to install trialware (9to5’s article used vmware/parallels, maybe because they have bought it?).

  • Hi, I’m amazed that the comments on this are still so recent – would be amazing if someone can give me a helping hand with this.
    I’m trying to get Win7 working from an external FireWire drive (Macbook pro mid 2009, OSX El Capitan). I’ve tried the tutorials here as well as the two below; the installation seems smooth either way and mac recognizes the external hard drive as windows drive after restart (holding option key). But after selecting the windows option, I end up with a “No bootable device – insert boot disk…” error


    2. (I’ve adapted the Disk and partition IDs to match my system)

    Would be fantastic if someone has experience with this and could give me a hint!


  • I tried doing this but it isn’t working, then I had to fix my partition schemes. Now I get this error…
    VBoxManage: error: VMDK: could not create new file ‘“bootcamp.vmdk”’
    VBoxManage: error: Error code VERR_ALREADY_EXISTS at /Users/vbox/tinderbox/5.2-mac-rel/src/VBox/Storage/VMDK.cpp(3392) in function int vmdkCreateRawImage(PVMDKIMAGE, const PVDISKRAW, uint64_t)
    VBoxManage: error: Cannot create the raw disk VMDK: VERR_ALREADY_EXISTS
    VBoxManage: error: The raw disk vmdk file was not created

    How do I delete this and start over?

    • I did delete the file but I still get…

      VBoxManage: error: VMDK: could not open raw disk file ‘/dev/disk10’
      VBoxManage: error: Error code VERR_RESOURCE_BUSY at /Users/vbox/tinderbox/5.2-mac-rel/src/VBox/Storage/VMDK.cpp(3416) in function int vmdkCreateRawImage(PVMDKIMAGE, const PVDISKRAW, uint64_t)
      VBoxManage: error: Cannot create the raw disk VMDK: VERR_RESOURCE_BUSY
      VBoxManage: error: The raw disk vmdk file was not created

  • Thank you for this great how to!!
    Somehow, I keep failing at this. This is the error I get when I try to “Create a VirtualBox Virtual Machine for Windows”. I receive this error:
    Failed to open the disk image file /Users/myname/bootcamp.vmdk.

    Could not open the medium ‘/Users/joelibby/bootcamp.vmdk’.

    VD: error VERR_RESOURCE_BUSY opening image file ‘/Users/muname/bootcamp.vmdk’ (VERR_RESOURCE_BUSY).

    Result Code: NS_ERROR_FAILURE (0x80004005)
    Component: MediumWrap
    Interface: IMedium {4afe423b-43e0-e9d0-82e8-ceb307940dda}
    Callee: IVirtualBox {9570b9d5-f1a1-448a-10c5-e12f5285adad}
    Callee RC: VBOX_E_OBJECT_NOT_FOUND (0x80BB0001)

    Any tips would be appreciated!

    • Hello Joseph,

      I just fixed this issue after a bit of tinkering. You need to assign your user ownership of the external disk.

      This can be done using this command:

      sudo chown MYUSERNAME:staff /dev/disk#

      (Fill in your username and disk number)

      Once you have done this run this command (do not run as sudo):

      VBoxManage internalcommands createrawvmdk -filename bootcamp.vmdk -rawdisk /dev/disk#

      (replace the # with your disk number)

      After this make sure the external drive is unmounted from MacOS and you will be able to add it to the Virtual Machine.

      Hope this helps!

  • Is it possible to do this but partition the drive so I could assign part of its storage to windows 10 and part to storing things from my mac (so MacOS)?

  • This is the error message I got:
    Last login: Sat Jul 21 10:05:56 on ttys000
    Johns-MacBook-Pro:~ johnscardina49$ sudo VBoxManage internalcommands createrawvmdk -filename bootcamp.vmdk -rawdisk /dev/disk4
    RAW host disk access VMDK file bootcamp.vmdk created successfully.
    Johns-MacBook-Pro:~ johnscardina49$ sudo /Applications/
    objc[2318]: Class FIFinderSyncExtensionHost is implemented in both /System/Library/PrivateFrameworks/FinderKit.framework/Versions/A/FinderKit (0x7fff96ea28b8) and /System/Library/PrivateFrameworks/FileProvider.framework/OverrideBundles/FinderSyncCollaborationFileProviderOverride.bundle/Contents/MacOS/FinderSyncCollaborationFileProviderOverride (0x1138e9dc0). One of the two will be used. Which one is undefined.
    objc[2318]: __weak variable at 0x7fe82ac4a4a0 holds 0x4031000000000000 instead of 0x7fe82ad656e0. This is probably incorrect use of objc_storeWeak() and objc_loadWeak(). Break on objc_weak_error to debug.

    objc[2318]: __weak variable at 0x7fe82ac2de70 holds 0x5e9 instead of 0x7fe82ad656e0. This is probably incorrect use of objc_storeWeak() and objc_loadWeak(). Break on objc_weak_error to debug.

  • The comments & follow-ups on this article have been extremely useful for me to chip away at a few issues I was having in trying to install Win 8.1 onto a USB 3 external drive …

    I’ve now got to the stage where I can dual-boot (N.B. at startup only ie still get bless tool error when chosing the folder in Start Up manager within System Preferences !) to a Samsung T5 from my MacBook Pro (15-inch, 2017) to finalise the install however …
    I immediately get a BSOD stating :-

    Your PC needs to be repaired
    The Boot Configuration Data file is missing some required information
    File: \BCD
    Error code: Oxc0000034

    Any ideas or pointers, anyone ?

    • I have exactly the same problem – any success on this one?

    • Hi Bill, I had the same issue and solved it by NOT shutting down the virtual machine before the first restart but waiting until it restarted and showed the Windows customize/setup screen. Then I powered off, restarted the MAC and finished the WIN installation. Now everything works just fine.

  • Hi, I tried to do everything right,
    I’m not sure if this caused my problem – but I used Paragon to NTFS format instead of FAT-32.
    Anyways, I couldn’t see my drive in macOS’s Drive Selection during boot up. I used rEFInd/refind and tried to boot into the drive, only to see the error found in this video:

  • Hi,
    I did everything right, windows boots fine, but I cannot complete the installation process (and subsequently install the drivers). In fact, the keyboard or the trackpad don’t work and hence I can’t click on next or anything to finish off windows installation. Any ideas?

    I have a new MacBook Pro 15’’. Could it be that the hardware is not compatible and needs drivers? If so, can you think of a workaround?

  • Hi–I installed to the external drive and closed VMware before it could restart. When I restart my computer and held down the option key, only Macintosh HD appeared as a choice. Not sure what I did wrong. Can anyone help?

  • And yes, I tried 9to5 mac procedure using vm ware fusion 10 and Teyadi external ssd. It didn’t work for me. Windows 10 in vm is unable to identify the external ssd. Seems some kind of problem with VM ware drivers or windows drivers but it won’t appear in explorer or disk management. There is yellow exclamation mark as well in the device manager. So, this workaround is surely better for those who can’t get the former work for them.

  • Have finally been able to install win 10 pro. This is difficult for novices. Above mentioned steps will work well with moderate users. A video tutorial or snaps alongwith steps will be very much helpful.

    I found trouble in following areas:

    Couldn’t locate the ‘home folder, initially. On mac, go to users and the folder (probably computer name in windows) is your home folder. Will be displayed as home icon.

    There is an error in the code where you have to create bootcamp.vmdk through terminal. Please ensure that you don’t use quotation marks in the code. If you have anyway, then go to home folder and remove the quotation marks by (rename the file).

    Couldn’t get the installation started in vm right away, it gave some error ‘FATAL: No bootable medium found! System halted’. Go to storage, remove any ’empty disks attached to any sata port and ensure that there are only two, one is bootcamp.vmdk and other is your iso file. First one is at SATA 0 and other is at SATA 1 (if you don’t have any more drives). Then go to system and change the boot order by prioritising optical disk over floppy or hard disk.

    Trackpad and bluetooth are still not working. Track pad doesn’t click or right click and unable to pair Logitech mouse through blue tooth. Will update as soon as I find solution to this.

    This helped me.

    • Regarding trackpad not working(soft click), its some sort of problem with windows 10 user accounts.
      Go to user accounts, create another account (administrator), log off from your default administrator account, log in to your newly created administrator account, go to user accounts and change the default account from administrator to standard. Now log in to your default (now standard account) and bootcamp control panel in the task bar should work fine. After the trackpad, you can again change account to administrator, if needed.

  • I am unable to select the bootcamp.vdmk file. The Virtual box software has been moved to Oracle’s site and appears to have been updated. Is there a way to use the app to create a .vdmk file? It wants to know if the choice should be dynamic, fixed or split.

  • Hey, i got a problem with boot camp assistant. it only shows me the option for partition and installation of windows. there is no such thing as “download the latest windows support…” where else can i find the correct windows installer and drivers??

  • Solution to VERR_FILE_NOT_FOUND: you must open Disk Utility to eject only the disk volume (not Finder). For example, if the physical disk is represented by disk3, eject only what is represented by disk3s1.