Mac & macOS

Instructions: Install Windows 10 on Mac on an external SSD

This is how you start Windows 10 on the Mac without Bootcamp

Do you want to use Windows 10 on a Mac? Then you probably sit down Boot Camp. Officially endorsed by Apple, easy to set up, why not. But there is a second option: Install Windows on an external hard drive, such as a lightning-fast SSD, and boot your Mac via USB. The magic word is Windows-to-Go. We show you how you can use Windows on the Mac from an external disk. 

Windows-to-Go as a Boot Camp alternative

As said earlier, the official Apple solution for Windows on Mac is Boot Camp. The downside: Windows takes up too much space on the internal hard drive, which can be particularly annoying on Apple's outrageously expensive SSDs. Also, you cannot use Boot Camp in combination with Apple encryption File Vault use, which is suboptimal for MacBooks in particular.

Boot Camp Windows 10
Boot Camp is the official solution for Windows on Mac, but it's not always the best.

An Windows to Go installation circumvents these problems. Here you install one nearly Full Windows 10 on a external hard drive (or a USB stick, but that's not much fun ;) ). When booting up the Mac, you then select the USB hard drive as the boot device. You will notice the functionality after the initial setup no major difference more when using Windows 10 on Mac.

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Another advantage: you can use the Windows-to-Go drive use multiple Macs (or on a PC, but that's another topic ;). I tested the number on a 2015 MacBook Pro and a 2013 MacBook Air, among other things, and was able to use Windows normally on both computers. At the iMac Pro (and possibly future 2018 Macs) you have to help a little, see comments...

Windows 10 Mac SSD
Windows on the SSD on the Mac is an excellent solution, especially for occasional use.

But there is one small disadvantage: the major updates for Windows 10 that appear every six months (like the Creators Fall Update) are denied to the USB Windows. But there are workarounds for this, which we will present in good time. You will find out the few other differences between Windows-to-Go and a full installation at Microsoft.

Windows-to-Go on Mac: What do I need?

Officially, Windows-to-Go is reserved for the Enterprise version of Windows 10 and limited to certain certified USB devices. Various free tools allow you to set up Windows on a USB drive, even with the other editions of Win 10. If you want to use Windows 10 permanently, you will of course need one legal activation key – if you don’t have one, you can find these for a few Markfuff hiss at Amazon and Co.

To make the external Windows fun, I recommend one external SSD or an SSD (alternatively, you can of course also use a built-in SSD in a suitable USB enclosure pack). Of course, all this also works with a classic external disk or a USB stick, just a little more comfortably ;)

make windows faster
An SSD is the best solution for installing Windows 10 on Mac.

Last but not least: You need access to a Windows PC to create the Windows to Go installation. If you don't have access to a Windows environment either at home or in your circle of friends, you can also use the number virtualization solve. Load one if you need it Windows VM down and directs the USB hard drive to this – not comfortable, but it works ;)

Everything ready? Then go for it!

1. Download Windows 10 as ISO

First download the current version of Windows 10. Microsoft offers the direct ISO download for free. Very important: The Rufus tool used in the instructions is coming not with Windows 10 ISOs created with Micrsoft's official Media Creation Tool. If you do not carry out the Windows download on the Mac but on the Windows PC, follow the steps that Mirco in this tutorial shows.

Download Windows 10
Download Windows 10 directly from Microsoft without detours via the Media Creation Tool.

2. Download Boot Camp drivers

Even without installing Boot Camp, you need the Boot Camp driver package, which Apple provides for free. On the Mac on which you want to use Windows-to-Go, start the Boot Camp Assistants. Now click in the menu bar Actions, chooses Load Windows support software and saves the download package so that you can access it later under Windows - for example on a USB stick.

Boot camp driver download
You can't do without Boot Camp ;)

3. Download and install Rufus

Now it goes on under Windows. We use the open source tool Rufusto create a Windows to Go installation. Load the program down here  and installs it. By the way: With WinToUsb there is another alternative, which, however, only releases some of its functions against payment. If for some reason you can't get along with Rufus, try WinToUSB.

Rufus download
Rufus brings Windows 10 to the external SSD

4. Create a bootable Windows installation with Rufus

Now connect your Windows To Go disk to the Windows PC and start Rufus. Here you first activate under Advanced Settings... the point Show USB hard drives. Then you choose Drive the USB disk. Now you choose by clicking on the button next to Create a bootable drive with the downloaded Windows 10 ISO file, tick it Windows to Go installation and starts the process with one click Home.

Rufus Windows to Go
Tick ​​a few boxes and off you go.

5. Select Windows edition

Before we start, Rufus will ask you about it Edition of Windows 10. Click on the version you have a key for and then click on Ok. Rufus will now create the Windows 10 boot disk.

Windows 10 editions
Microsoft and the Windows editions - always a horror :)

6. Boot Mac with Windows hard drive

Congratulations, you now have a working one Windows installation on an external hard drive. Now disconnect it from the PC and plug it into your Mac. Now restart it and hold when switching the key Old or options pressed. This tells your Mac to boot from an external drive. Select the entry in the displayed start menu EFI boot off - this is Windows 10 on the external hard drive.

Windows 10 Mac boot
The external hard drive with Windows 10 appears as boot medium

7. Set up Windows to Go installation

When you start it for the first time (which can take a little longer), Windows 10 will set up everything possible, including a step-by-step wizard - just as if you were installing it "normally". Make sure that the system in between once restarts. If you don't press the Options key, you'll end up back in macOS. But it doesn't matter, just restart the Mac and boot back into Windows. Don't be surprised if you can't connect to the Internet without a driver at this point, we'll catch up on that in the next step.

Windows 10 to go setup
Setting up Windows-to-Go is exactly the same as with “real” Windows 10

8. Install Boot Camp drivers

Once you land on the Windows-to-Go desktop, you can complete the installation. To do this, you connect the stick with the downloaded Boot Camp drivers, unzip them and start the file Bootcamp.exe. Wait for the driver installation and restart the Mac at the end to be able to use all hardware functions.

Boot camp driver windows 10
Once the Boot Camp drivers for Windows 10 are running, your USB Windows is ready to use.

9. Complete Windows installation on external hard drive

Well, that's it at last! After the restart, you can use all the functions of your Mac under Windows 10, just as if you had installed the system via Boot Camp. After Windows 10 has connected to the Internet, you will sooner or later after the activation key asked. Enter this to activate Windows. Congratulations: You now have a fully functional Windows installation on an external hard drive on the Mac! You can now work normally with Windows 10 on the Mac, including all programs and games. Do you want switch back to macOS, you just have to restart the Mac without the option key.

You can find even more tips and tricks about macOS here here, but there are dozens of Windows tutos here to discover.

Boris Hofferbert

Freelance journalist, enthusiastic about technology since the blissful Amiga days, Apple desktop fan and Android fan on the go, gambles on Windows, can’t do without music (from classic rock to ska to punk) and audio books, likes to take postcard photos, always has at least two cell phones and is very happy about one coffee donation ;-)


  1. Hello Boris,
    Thank you very much for this great idea! I've asked Apple several times if I can use my already set up Wins-to-Go on my MacBook. The answer was several times: no!
    Now I'll ask you again directly: I already have a Wins-to-Go set up, which I always connected to my WS laptop.
    What do I have to do now so that I can use the wins-to-go I have already set up on the MACBook?
    A thousand thanks in advance

  2. Unfortunately I have the problem that I can't get it to work.

    It's a 2020 MacBook Air with an i7 processor.

    I downloaded the Bootcamp drivers on the MacBook and saved them to a USB stick.

    I created a Win to go USB stick with Windows 10 via rufus.
    But as soon as I boot from the stick, I only get to the first Windows settings menu where you can set the time and language, then an error message appears, i.e. "Windows has detected an error and must be restarted". It then goes on like this forever.

    And it all takes forever, it takes at least 30 minutes for the error message to appear. It is loaded forever, i.e. Windows logo and a “loading circle” underneath.

  3. Hello Boris,

    I have a Bootcamp Windows partition that has already been set up on the internal HDD of the MacBook Pro under Big Sur / Monterey and of course I would like the set-up applications to be on the external USB SSD
    "take along". How do I go about it (or does it still work the same way) and how can I then do the Bootcamp partition part d. internal HDD again for d. convert mac ?

    Thank you

  4. Hallo,

    I've been trying to start the bootcamp exe for hours.
    I keep getting the same error message. The device has encountered a problem. It needs to be restarted. It collects some error information and then reboots.

    0% complete


    Who can help me???

    Thank you very much for your help

  5. Hello!

    Can anyone tell me if it's safe to do all Windows updates? On mactechnews someone says that updates can destroy the installation, I have version 1909 installed, so far no problems with updates, but now I'm afraid I'll have to redo everything.
    Thanks for info! I've already looked at RegEdit for the value "Portable Operation System", which isn't even available here.

    1. Hi Stefan, I've been using WIN 10 on an external SSD for about 15 months and I do every WIN update regularly, and there have never been any problems.

      1. Does anyone have any idea how I can boot my mac automatically into win 10? It doesn't appear on the start volume

  6. Overall, this guide and comments saved my home office. Unfortunately, DLZ Bayern only supports Windows, so I first tried it with a virtual Windows machine based on VMware Fusion 12 and Win 10 Pro. But it all went more badly than right. Since I already have two macOS versions running on external hard drives, I wanted to run Windows in the same way. That's how I came up with this guide. Unfortunately I only had problems with Rufus and WintoUSB: Somehow nothing worked with Rufus and with WintoUSB I could only have installed Win 10 Home?. I then read about HDclone in Rainer's comment. I figured why not clone the VM with it and see what happens. What can I say, it actually worked and led to success. The iMac booted from the disk with the cloned VM with no problems, and then all I had to do was install the Bootcamp drivers. Of course, there was still a catch: The clone now lacked the connections to the respective storage locations of the VM. Since I have absolutely no clue about Windows, I radically reset it. Now everything is going as you would imagine.

  7. Hallo,

    Up until now I had installed Windows 10 “To-Go” via WinToUSB (the free version), and then installed the Boot Camp drivers.

    Everything worked, including the camera - but NOT the sound (neither playing nor recording). And this on an iMac 27″ 2017 (i7, 32 GB RAM, Radeon Pro 580).

    According to Is this because Windows 10 runs in "UEFI" BIOS mode instead of "Legacy" BIOS mode - which is actually the case for me (via WinToUSB)!

    There are people who somehow got the sound to play “via boot loader manipulations”:

    but the steps there definitely go too far for me ;) But at least it confirms the connection between "BIOS Mode" and the sound card.

    By the way, I'm NOT seeing any device conflicts/issues, and I've repeatedly updated (via macOS) and reinstalled the Boot Camp drivers.

    I'm currently doing a "To Go" Windows installation via Rufus (as described here).

    But a quick question (because, interestingly enough, no one reported sound problems here): does it work for someone here in the forum with the sound (via Rufus)? If so, did drivers from the original manufacturer or something like that have to be installed afterwards? In which "BIOS mode" (via msinfo32.exe) does Windows 10 run? UEFI or Legacy?

  8. Since some are interested here:
    I just did the big update from ios Mojave to ios Big Sure. For my part, I can say that WIN10 on the external SSD, which previously ran perfectly under mojave, now runs normally.
    My computer is an iMac 27" from 2019.

  9. Hi all,
    I also have a problem with the installation.
    About my system: MacBook Pro 2018 with Mac OS Big Sur.
    I followed everything as in the tuto, downloaded the ISO file on the Mac, then created it on a Windows PC with Rufus Windows To Go on an SSD.
    Connect booted via the SSD and Windows set up so far.
    It all worked and I can basically access Windows as normal, but apparently the Bootcamp drivers that I loaded onto a stick cannot be installed correctly. During the first installation and after restarting the Mac, I still couldn't connect to WiFi or connect a Bluetooth mouse.
    I then installed the driver again or repaired it, but then the installation got stuck with a completely green "progress bar" and nothing more happened. Exactly the same thing a second time: Status bar got stuck at Status: Apple USB Virtual Host Controller and nothing happens anymore...
    I've already formatted the SSD, reinstalled Windows on it, downloaded the drivers again, but I keep having the problem that I don't have a network or Bluetooth connection, etc.

    Does anyone know how to solve this problem?

  10. Hi all,
    I did everything like this for my MacBook pro 2020 and the Win disk works and is even set up. After running Bootcamp.exe, which was supposed to set up the drivers for Win for the hardware, nothing happens - no error message - but also no support for the WLAN and LAN module, no keyboard and mouse - not to mention the touch bar and the trackpad. Are there drivers elsewhere? Does anyone have any advice - I'm exhausted and at the end :-) Thank you for the hints

  11. It doesn't work for me. After selecting the boot medium, the Apple logo appears and he wants to reinstall MacOS, speaks WIN10 does not even start. What am I doing wrong? MBP 2019

    1. The MBP 2019 has a T2 chip. You must first disable Secure Boot in macOS recovery mode and allow booting from external media.

  12. Hi all,

    I used the instructions and installed Win 10 on an ext. SSD installed to play. Everything worked smoothly for at least 10 months. Until yesterday.. Windows constantly crashes or hangs up so much that nothing works without a hard reset. I can get into Windows, but after 60 seconds at the latest it hangs. It doesn't matter whether I want to connect my magic mouse and keyboard, or just press the Windows key without going into the settings. The problem occurs after the last Windows update. Is it possible that I need more up-to-date drivers, or is my Windows broken? If the latter: How can I perform a system repair with Win-ISO under these circumstances? Just drag the ISO onto a stick and then boot from that?

    Thank you in advance!

  13. With a MacBook Air (2020) with Catalina 10.15.5, Windows 10 always crashes on the external SSD when installing the driver with a blue screen and the message driver_verifier_dma_violation.

    Does anyone know remedy?

    1. The Air 2020 has the T2 chip just like the Mac Mini.
      Haven't managed to install Win10 externally on the Mini yet.

      I'm currently using a 60GB BootCamp partition and have installed all the games and programs on the external SSD (for me it's a pure gaming system with eGPU).

      Everything else is used under MacOS

      1. It shouldn't be the T2 chip. I run Windows externally on my MacBook Pro 2019, which to my knowledge also has the T2 installed.

      2. Have a look above. On April 6th I wrote a relatively long comment with a few additional steps to this guide here.

      3. Did you download the drivers with the MacBook Air that you plan to later install them on in Windows?
        I can imagine that there are specific versions.

    2. I can confirm this behavior. Will we have to wait for an updated Bootcamp driver version, or have you already solved the problem? I haven't tried an internal installation - is that possible?

      1. No, I haven't found a solution yet.

        I haven't tried it internally as there isn't enough space.

  14. So on my iMac 9,1 from 2019 with Mojave 10.14.6 and a Radeon Pro 580X the instructions worked great - thanks again for that. I wanted this mainly for gaming, for working with Win10 I use VMWare. The only thing I can't get working is Bluetooth, meaning I must have a USB keyboard and mouse plugged in and neither the BT headset nor the BT controller from the Playstation works on Win10. Is there a solution or is it just me having the problem?

  15. Hello, thanks for the detailed instructions.
    Everything worked perfectly. Only in the final step after I installed the Boot Camp drivers and rebooted, the drivers still don't work. So still can't use my keyboard, trackpad, wifi, etc.
    Does anyone know the problem or a possible solution?
    I am using the new MacBook Pro 13'' (2020).
    Thank you!

    1. I fixed the problem. I updated the drivers through Device Manager.
      The non-functioning drivers are marked with a "!", you have to update them and let the system search in the Windows Support folder.
      Only the Touch Bar is still without function. Does anyone have any ideas for a solution?

  16. Hi! Got a MacBook Pro 2019. successfully created the external usb-x SSD. Then adjust the startup security on the Mac. then started with option, EFI booted. Windows Setup starts. From the choice of the installation partition, does Windows write that it cannot be installed on USB media?

    Anyone know why?


    1. When creating the Windows ISO file on the external hard drive, did you make sure to check the "Windows-to-Go installation" box?

      1. I think so! Will try again, with wintousb I can't do it at all, because it always breaks off at 0% when creating the Windows SSD

  17. Hallo,
    Thank you for the good and detailed instructions.
    With WintoUsb I finally managed to get Windows running via a USB stick
    small suggestion:
    Maybe you can already include in the post that on some MacBooks (including my MacBook Pro Retina 2016 Touch Bar) the keyboard and trackpad don't work until the drivers have been installed via the Bootcamp installer, which you can only do if you have one Connect USB mouse and keyboard.

    Luckily found the clue in the comments when I was almost giving up.
    Would have been more relaxed to be referred to beforehand.

    Nevertheless thanks so far!!!

  18. Hello, first of all thanks for the great guide. The installation worked on my MacBook pro with Mojave. I now have two iMacs 27″, with both IMacs the hard drive is not recognized when booting. Have I misunderstood something and the installation only works on the computer on which the Windows boot drivers were created or should the hard drive also be recognized by the other Macs? Chip sets and OS versions are identical.

  19. class guide,
    I tried the whole thing last weekend with my MacBook Pro (2019) with MacOs Catalina (10.15.4), everything worked, but I had some difficulties and wanted to add a few things to the existing instructions.

    Since the new Macs put even more value on "security", you have to make a few settings on the Mac yourself before you can boot the SSD with Windows.

    In the “Boot Security Utility” under “Secure Boot” you need to check the “No Security” box.
    Furthermore, under "External booting" the tick "Allow booting from external media" must be checked.

    The boot security utility is invoked as follows:
    Turn on your Mac, then hold down Command (⌘)-R immediately after the Apple logo appears to boot to macOS Recovery. When the macOS Utilities window appears, choose Utilities > Startup Security Utility from the menu bar

    Then even new Macs can be booted from a hard drive.

    It should also be noted that when Windows is installed, no drivers for the Mac are included and therefore (at least for me) the keyboard and mouse pad are without function. So you still need a USB keyboard and/or mouse.
    However, this creates another problem. If you have Windows running on a hard drive and the BootCamp drivers on a USB stick, there is no more room for a mouse or keyboard on MacBooks with only two USB ports.

    Luckily I had a hub lying around at home that offers space for an SD card in addition to the two USB ports. So I pulled the drivers onto the SD card and was finally able to do everything as described in the instructions.
    However, you should keep this in mind if you want to do the whole thing on a MacBook and prepare yourself accordingly.

    1. Now that everything is fully installed, can you also use your Macbook keyboard under Windows or do you still have to work with a USB keyboard?

      1. Once the drivers are installed, the MacBook's keyboard and trackpad can be used without any problems.

  20. Hallo,
    I have followed the instructions on my MB Pro 13' without touchbar so far.
    Up to the selection whether you want to start macOS or Windows, everything works as described.
    But then nothing works anymore. After selecting Windows, the HDD stops blinking and the screen stays black.
    Can anyone give me any tips that will help? Connected the HDD to the TB3 port using a small dock. Does it have anything to do with this?

    1. Great, thanks for the feedback.

      Unfortunately, I don't have the right hardware at hand at the moment to check that the tutorial is up to date, so information like this is extremely valuable :-)

  21. Hello everybody. I followed the tutorial step by step, but unfortunately it doesn't work on a Mac Mini 2018 with version 10.15.3 macOS Catalina. I can't say yet whether the T2 chip is to blame. I adjusted the security settings. Security down and external boot allowed. Unfortunately, I always get the message: "bless tool could not set the startup volume", which prevents booting from the Windows SSD.
    Unfortunately, I can't test whether the whole thing would work on an earlier Mac, since I only have the 2018 Mac mini. On a Windows computer, booting from the external SSD Windows version worked without any problems, which at least gives me the satisfaction that Windows is executable!
    If anyone knows a solution for this bless tool message, please post it here, because my internet research on this topic has so far been unsuccessful!
    (Stand 13.02.2020)
    MfG Daniel

    1. Small update: the Windows SSD worked on a 2013 iMac with Mojave.
      So it seems to be due to the innovations of the 2018 model.
      Further research revealed other possible problems.
      – The T2 chip could still be the main problem
      – Due to the permanently installed flash memory, external disks are generally not accepted as boot disks (theory)
      - maybe it's the USB ports - I read somewhere that one made it with an external Tb3 disk (I'll consider it for further attempts)
      Updated 14.02.2020
      happy valentines :-)

      1. I have the same problem as you, 2018 MacMini i7, 32GB RAM and 500 SSD and Rauer Core X with Vega56.
        But starting Windows 10 from an external SSD does not work at all.

        It is supposed to work with an external TB3 SSD as it is recognized as an internal drive. The Samsung X5 for example, but this costs a lot of money!

        Otherwise, only boot camp will remain and then connect the external SSD there for installing games, programs, etc.

        If you have any news, get in touch :)

  22. Hello Boris,

    thank you very much for this guide. It works! The installation worked with my MB Pro (2017) with touch bar without any problems. In addition to a 256 GB SSD from Intenso, I also got a USB mouse, I had a USB keyboard there.

    In my fresh WIN10 to-go, I only encountered the problem that I could not access my network via WLAN. Connected by cable, Apple software update performed (WLAN driver update was available), cable disconnected = I got into the network but no Internet access. WIN troubleshooting, restarts, etc. have brought nothing. The solution was probably to reconnect the MB under WIN to-Go with a cable to the router and then also connect it to the same network via WLAN. I then removed the cable and since then I have internet in the network, even after restarts. I have no idea why but it helped me in case anyone else had similar problems! :)

    I am now super happy that I no longer have to shrink my internal 512 gb SSD with Bootcamp!
    Thanks! :)

  23. Servus people

    I created a Windows ToGo on an external SSD. This is connected to the MacBook Air via USB and booted. So far everything without errors.

    But the keyboard of the MacBook is without function. A USB keyboard works fine. Even after all Windows updates and the installation of Bootcamp drivers, the internal keyboard still doesn't work. Why ?

    Thanks in advance

  24. I did it as described with an external SSD. But my Macbook Air can't access the data - it just doesn't work. What can be the reason?

    Best regards,

    Burkhard Klas

  25. Hi all,
    First of all a great guide - thank you!
    I managed everything as described.
    However, WIN10 starts extremely slowly and I don't know why.
    I installed windows on a msata ssd. This is in a housing and is connected via USB. I have already tried it via a USB HUB which can be saved via Thunderbolt.
    Maybe you can help me on how to speed up WIN.

  26. Hallo,
    Very good guide.
    I have only one problem:
    When burning the ISO file to my external SSD, Rufus always gives the error message that the actual file could not be unpacked, how can I fix this error?
    Many thanks for the help :)

    1. Did it exactly as in your guide but I couldn't get the WIN 10 installer to finish installing to the Samsung X5 drive. No matter whether reformatting with the installation routine, deleting and starting the installation or formatting the disk beforehand. The routine hangs during the installation ;(

      1. The best way I can get is to erase the disk during the install and with the unformatted area (shown as "unallocated space") selected, click the Next button.
        In the next step, i.e. the one where the data is copied, this error message appears:

        The computer could not be prepared to start the next phase of the installation. Restart the installation to install Windows.

  27. Thank you for your instructions, it worked great!
    As you mentioned, the major updates don't work, I installed W10 (1803), refusing to update to 1809 W10. It's not that bad.

  28. Thank you for the great contribution!

    Unfortunately, despite everything, I encountered an obstacle. I use a MacBook Pro 13 inch with touch bar, 8 GB RAM, MacOS High Sierra (currently 10.13.6).
    Since I was using a somewhat more recent version of RUFUS (3.4), the interface looked a little different, of course. I think now the program can handle ISO files created via MediaCreationTool - at least that was the case for me. I shut down my MacBook, connected the external hard drive (HDD) and then restarted the notebook (by pressing the option key). I was actually able to select and start EFI-BOOT – the typical Windows 10 icon loaded for a brief moment – ​​but then I was redirected to a blue screen. A grey, windows-typical window (from 1990 rather than 2019) asks me to select the keyboard language etc. Unfortunately, this doesn't look like a standard Windows OS installation at all... but to my great frustration (having gotten this far), the notebook doesn't respond to anything at all. No enter input, no mouse pointer appears that could be moved over the touchpad - nothing.

    Do you spot the mistake or anyone else here reading the comments?
    Maybe RUFUS 3.4 also needs a different ISO file? But then I certainly wouldn't have gotten as far as being able to select EFI-BOOT at all, i.e. the formatting of the hard disk would have failed?
    When formatting with RUFUS, should I have selected FAT32 LARGE instead of leaving it at NTFS? (Since Mac often bitches about this format.)
    Where did I do something wrong?
    By the way, saving Windows Support from Boot Camp to a USB stick also worked great, otherwise had no problems, but something seems to have gone wrong on the way ...

    Thanks in advance for any (helpful) answer! :-)

  29. Hallo,
    I'm looking for a way to upgrade the Windows (Win10 - 1803) installed on the USB_SSD to version 1809. Is there a way to do this with free resources?
    Does anyone know a link to a freeware tool?
    Thank you Rainer

    1. Yes! I was able to install it with Flashboot 3.2. However, I get the error message when booting: inaccessible boot device

    2. Hallo,
      the following procedure helped me (upgrade from 1803 to 1809):

      Tutorial to upgrade Windows To Go by changing the registry key value.

      Step 1. Start windows from the USB drive.

      Step 2. SRun regedit.exe as administrator.

      Step 3. SNavigate to "HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control" and change the value "PortableOperatingSystem" from 1 to 0

      Good luck!

      1. I don't have that value.

        Actually I don't care if Windows is upgraded or not, just afraid that some update might crash the installation, at least that's what someone says.

  30. Hi all,

    I have a MacBook Pro 13 inch without touch bar (date of purchase 12.2018 / according to system build 2017).
    Everything done as described above. It starts booting from the SSD (Samsung T5 SSD 250gb), then a message appears for a short time with a big :( smiley saying that this system isn't working or something similar and it starts booting again. I can't get to the "install" at all ". Does anyone know the problem or a solution? Unfortunately, the message is always so short that I can't read everything. I'm very grateful for solutions.



  31. Hello Boris,

    Thank you for the instructions. Only one thing is different for me: no matter which version (2.18 or higher) I use, I don't see the option "... to go". The installation without this setting does not appear to be executable after successful recording of the SSD, although the Mac (iMac 2009late) simply restarts, although it is visible in the boot medium selection. I'm at a loss (I can't get any further with WinToUSB).


  32. Hello
    only partially worked for me. Start as windows after rufus step ended in black screen. solution was:
    – Format the hard disk again after rufus under parallels virtual machine, both parts, the EFI part and the main part, both as ntfs
    – then load windows with wintousb on ssd then continue as described.

    I don't see the hard disk of the Mac under windows at all, can you not access it under windows with the apple drivers from bootcamp? or senn, how?


  33. hello boris, unfortunately I keep getting the same error message (standstill code Inaccessible boot device). do you have any solution suggestion for me?


  34. Hello, first of all thanks. Unfortunately, it doesn't work for me (Macbook Pro Retina, Mid 2015) because I can't download the "Windows Support Software" from the boot camp. It breaks me every time with an undefined error. Accordingly, I now have a Win10 on the external disk, it can also start on the Macbook, but it is worthless because the version does not have a driver for the network adapter. So I can't get WiFi into the network.
    Will try again via cable to bring it to the network. Otherwise, my search for a driver package was unsuccessful, it seems that only under the
    Other experience adds: You need a pure Windows machine to install the ISO. Opening Windows under Parallels Desktop and then using Rufus does not help because Rufus does not recognize the drives.
    Do I have another idea? Thanks very much!

  35. Hello Boris,

    is there any news about the update of Windows-2-Go to the current Spring Craetors version (1803)?

    Yours, Rainer

  36. Hello Boris, first of all thanks for the great instructions.
    Unfortunately, I have a serious problem: First of all, everything can be installed perfectly, Windows also boots from the SSD. But when it comes to selecting a region etc., I notice that the keyboard on my MacBook (Pro, 2017, High Sierra) doesn't work. And from there I can't go any further, the BootCamp drivers for Win10 are on a stick, but Windows can't access it yet.
    What can I do?

    1. I'll answer myself: With a USB mouse and on-screen keyboard (I had overlooked them), it was now possible to complete the installation. Now everything is going very satisfactorily, thanks again!

      1. OK, this will be due to the fact that Windows does not have Bluetooth drivers when installed. As far as I can see, this should also lead to problems on PCs, since Bluetooth devices are (often?) not supported by the BIOS. In other words: When installing Windows, you should always use a USB mouse and USB keyboard – regardless of the computer.

  37. Hello,
    With the help of the instructions, I now have Windows 10 on an external USB-C SSD.
    Everything runs fine, but the graphics performance has totally collapsed (compared to Bootcamp and OSX).

    You don't notice it in Windows mode, but Valley, for example, only gives 5 FPS with HD resolution. In BootCamp it is at least 60.

    AMD drivers are installed.

    Using IMac 2017 with RX580.

    1. Update
      If I plug the drive into the USB Type A instead of the Thunderbolt port, the graphics performance is ok again.

      Unfortunately, the installation destroyed my standard BootCamp.
      Parallels says boot partition is gone.
      A direct attempt to start BootCamp failed.

      Anyway now my Windows is running from USB. Is much faster than before BootCamp.
      Everything is fine, only the fan control does not work automatically. Had to install utility.

      What are your experiences

    2. Update
      No idea why, but now the graphics performance is also great via Thunderbolt or USB C.
      Valley at Max 120 and min 60 at HD and Ultra Settings.

      The G Technology mobile was really worth it.
      USB 3.1 Ver2
      Read Write at 400 to 500 MB/s

      Windows is now felt 3 times faster than with BootCamp from HDD.

  38. Hello

    A nice tutorial. Now I wanted to try the whole thing today, but with Rufus I always got an error message that the ISO cannot be unpacked.
    Has anyone else tried a tip several times but always get the same error message.


  39. It's all well and good to be able to install Windows in principle, but you can hardly go online with this version.
    The Fall Creators Update cannot be installed and therefore there are no security updates. YOU talk about a solution, please share it with us :)

    1. Hi Mark,

      sorry for the late reply, missed your comment :-/ In fact, the solution is not "perfect" like Boot Camp (if you disregard the occupancy of the disk and the forced renunciation of FileVault, etc.), as nasty as you describe it, but fortunately don't eat it either :)

      First of all: If you get a fresh Windows ISO from Microsoft, you already have the latest update in it. This is currently the Fall Creators Update, in a few weeks it will be the Spring (?) Creators Update. I will use this to check in good time whether the upgrade methods for Windows-to-Go recommended in the forums work – stay tuned ;)

      Irrespective of this, the monthly Windows security updates also come without the "big" update packages for quite a while. You can install these Patchday updates as normal using the Windows-to-Go method shown and are therefore "safe". If you believe this blog, for example:

      the Fall Creators Update (aka "Windows 1709") will receive updates until October 2019 before having to update to the next package.

      Nevertheless: For me the Windows-to-solution is more of a solution for "Use Windows on a Mac with real hardware from time to time". The method is absolutely great for this. In everyday life I continue to use Parallels most of the time, if I needed Windows 10 productively every day, I would rely on Boot Camp...

  40. So first of all I would like to thank you Boris for this great guide!

    I have an imac and a mac book pro from 2014. In the past I used my imac via bootcamp for windows until I restarted my mac during an update and it was all over! I tried to install a new operating system for 8 hours last Friday. No chance. I could no longer partition the internal hard drive. Not even with "Terminal" from Apple and "cmd" from Windows and other programs. Bootcamp gave me an error all the time. That's why I came across this alternative here, which made me very curious, since I still use a Mac Book and am therefore more flexible.
    In the evening, out of frustration, I ordered the SSD disk and housing directly. Arrived yesterday, installed today.

    So now to the essentials:
    I tried to record the SSD with Rufus which didn't quite work for me. Since I couldn't select the item "Windows-To-Go" either, as can be seen in the screenshot above. I couldn't select the GPT partition scheme either. For this reason I used WindowstoUsb as mentioned above.

    During this time I still had problems with the recognition of the SSD on the Windows PC. At first I thought it was because the USB slot on the Windows PC wasn't supplying enough power, since the disk ran on my mac without any problems. After an hour I simply used a different case and thank God it worked. So here I just want to emphasize again that it often fails because of small things.

    When the hard drive was finished with WinToUsb, I connected the hard drive to the Imac as described. For me it was not Efi Boot in the start menu but quite normal Windows.
    Clicked on it and “…no bootable device…”…. tried several times no success. It then worked on my Mac Book. Without problems. Boot Camp installation too.

    Then reconnected to the Imac and now the system is running there too. I'm super happy but still had a few problems and almost 4 hours of work ;)

    But it was worth it!
    Thanks again Boris.

    1. EDIT: I completely forgot a question. Since the hardware is different from my Apple devices, do I have to install Boot Camp on both devices or do something else?

  41. Question to the author of the article:

    Which program is the best/easiest to use to create a 1:1 copy of the Windows-To-Go created in this way? It's always a problem without a backup and it's not possible to back up Windows-To-Go with the Windows on-board tools.

    Best regards

      1. Hello Boris,
        Thanks for the tip, Macrium Reflect Free seems like a good recommendation.
        Downloaded it and will try it on the weekend.

        Thank you!

        Kind regards Rainer

      2. Hello Boris,

        I tried Macrium Reflect today to clone my Windows-To-Go to another disk. It then took about 2 1/2 hours to clone the SSD, but after that I couldn't boot from the clone. Apparently the EFI partition is missing!?!
        can you tell me something about that
        Are there alternatives to clone a Win-2-Go bootable?

        Kind regards Rainer

      3. Hallo,

        I've now used HDclone 7.0.2 (freeware) and it gave me a 1:1 bootable copy of the Win-To-Go palette. Was also much faster than Macrium Reflect.

        Greetings Rainer

  42. I followed this guide and it worked for me on the first try. I previously bought a Win-10 Pro license for €4,20 in the bay and now have a stable Windows 10 on a 120GB SSD, which I use on my Mac Mini (Late 2012, i7, 16GB RAM) and my MacBook Pro (Late 2010, i5, 8GB RAM). I am 100% excited and fully satisfied. Thank you for the really good tutorial!

    Installing Windows updates and the Apple software/drivers worked great.

    I'm curious about the addendum regarding the 1/2 annual update of Windows, which is not supposed to be so easy to install on a Windows-to-Go. Would be great to get an email about this.

    Kind regards, Rainer

    PS: when booting with the ALT key pressed, three drives (MAC, Windows, EFI) are usually displayed, but sometimes only two drives (MAC, EFI). Why is that? Never selected WINDOWS, always EFI. And that has always worked well.

    PPS: my Apple Magic Mouse sometimes gets stuck and sometimes stops completely for a few seconds.

    PPS: A driver problem is displayed in Windows: "Driver problem with Bluetooth HID device" which I can't get rid of. Any idea?

  43. Nice guide.
    It just doesn't work with the current High Sierra (APFS) or current Macbooks and iMacs.
    I would like to spare my new iMac Pro a Bootcamp Windows installation because the disk is "only" 1 TB in size.
    Unfortunately, you can no longer extract the absolutely necessary Windows drivers previously loaded onto a USB stick by Apple and save them separately for later installation under Windows.
    This has been running in the background for several years, completely bypassing the user. In the BC Assistant, there is simply no longer a point where you could select "Load driver".
    The author writes an article on this topic in January 2018 and tests it on devices from 2013/2015.
    Those who operate these older models might be lucky to find success following this guide.
    However, current MacOS and Macs cannot be persuaded to make external SSDs executable with Windows.
    And then there's the new APFS file system, which poses completely different hurdles. But have fun tinkering. In any case, I have not been able to successfully get an SSD running with Windows 10 on the Mac with great effort and time and with the support of Apple Support (the higher-level technical hotline).
    If the author also has a solution for this (current Macs and Mac OS 10.13.2), I would be very happy and I would ennoble him personally.

    1. Hello Martin,

      Thanks for your detailed and constructive comment, I like it that way :) In fact, I currently don't have the opportunity to test the whole thing on a 2016/2017 Mac, but I can do it with a friend at the beginning of February.

      But what makes me suspicious: I wrote and tested the instructions on High Sierra 10.13.2, including APFS-converted AND File Vault-encrypted internal SSD (as described in the 2015 MBP). With the method described, however, the internal Mac file system is not touched in any way. I don't really see any problems here - or has Apple changed anything radically with the models from 2016?

      As far as the drivers are concerned, I'm actually stumped. Maybe Apple hasn't released them for all models with High Sierra yet...? Just tested it with Boot Camp Assistant on brand new macOS 10.13.3 and got a normal folder with an EXE file. As I said, MAYBE Apple hasn't released the stuff yet, but then Boot Camp (and not just the function with the external hard drive) wouldn't currently work on the models at all.

      But it can only be a temporary phenomenon, because in this video the good Lon Seidman does a similar trickery on a 2016 MBP with WinToUSB instead of Rufus. Is of course still under Sierra instead of High Sierra:

      As I said, I'll keep at it, but it may take a while ;)

      1. Hello Boris,

        Thank you for the detailed instructions. Unfortunately, I can only get to point 6 (boot Mac with Windows hard drive). There I then select the EFI Boost. The Windows logo appears, it restarts, I press "Option" again, after 2 minutes Windows logo comes a blue screen with the following information:

        "Your PC ran into a problem and needs to restart. We're just collecting some error info, and then we'll restart for you.


        What failed: dump WppRecorder.sys"

        Then the Mac restarts under Windows and the error comes again etc.

        I have an iMac 27k (2017) with MacOS Mojave. I created the installation file with Rufus on a Windows PC (Windows 10 Pro 64 bit). Both with the current Rufus version and with the one used in the tutorial.

        I do not know how to continue. The problem solutions in the network regarding the WppRecorder.sys all refer to Windows computers.

        Do you have a solution for me?


      2. Hi Luke

        same here

        already found a solution?
        I switched from an intenso ssd to a Samsung ssd t5 - completely new installation because 256gb vs 250 gb cloning didn't work.


    2. Soooo, since the topic didn't let me rest, I did a little research. This could be an exclusive "feature" of the T2 chip in the iMac Pro, judging by this mac & i article:

      I can't really check THAT at the moment for various reasons... Christian, for example, has the download option for the boot camp software on his 2017 standard iMac and a normal folder with an EXE file also came out of it. At the bottom of the Heise article there is also something about a possible workaround for the boot process, you can check whether it works.

      Since said T2 chip is currently only used in the iMac Pro, I would say that the instructions still have a right to exist in January 2018....

    3. ...and as the last official act before the end of the day: Here is a description of how to change the Secure Boot behavior on the iMac Pro:

      Unfortunately, as I don't have an iMac Pro, I can't say whether the "Medium Security" setting is sufficient for the external SSD solution, or whether my previous answers are sufficient at least for a low nobility ;)


      Here is the information directly from Apple. Sounds a bit like disabling the option on the iMac Pro entirely and also allowing external booting. Brave, new, totally safe world :-/

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