How to Install Windows 8.1 from a USB Flash Drive [Updated]

Microsoft launched Windows 8.1 via Windows Store on Thursday. If you have several machines to install it on, here’s how to install it from a flash drive.

Update: Mainstream support for Windows 8.1 has ended. Here is the official lifecycle statement from Microsoft: “Windows 8.1 reached the end of Mainstream Support on January 9, 2018, and will reach end of Extended Support on January 10, 2023. With the general availability of Windows 8.1, customers on Windows 8 had until January 12, 2016, to move to Windows 8.1 to remain supported.”

Thanks to our readers, I’ve learned that this process won’t work using your Windows 8 key. Why Microsoft gives us the option to create an ISO of the 8.1 update but doesn’t allow the use of our existing Windows 8 key (it’s a free upgrade after all) I am not sure. Microsoft’s own page states:  “If you bought a Windows 8.1 or Windows 8 product key, you can download and install Windows from this page. You’ll have the option to install Windows now, later, or using media with an ISO file.”

One thing I was able to confirm is that using a Windows 8.1 key from TechNet or MSDN, the install goes off without a hitch. From what I’ve read, there are issues with this upgrade depending on the scenario, and this is definitely one of them. Hopefully, Microsoft will fix this issue. There are some workarounds you might want to try that our readers have pointed out in the comments below. I will continue to keep this post updated as we find out more.

The Windows 8.1 update was made available on Thursday this week, and for most Windows 8 users, the easiest way to install it is via the Windows Store. But if you have more than one system to update, it’s easier to create physical media to install it. This helps because you don’t have to worry about downloading a 3.5 GB file each time you update a different machine.

Install Windows 8.1 from Flash Drive

First head over to this Microsoft page and click the Install Windows 8.1.

Windows 8.1 Download Page

That downloads a small installer file that you run on your PC. After it downloads, simply run WindowsSetupBox.exe. Keep in mind that you’ll need Windows 8 running on the computer you’re installing the update on.


The Windows 8.1 Setup wizard will launch, and the first thing you need to do is type in your Product Key.

Enter Product Key

Now, wait while Windows 8.1 is downloaded. You can continue to use your system while it’s downloading in the background.


The next step will prompt you to decide if you want to install now, create media, or install later from your desktop. Select “Install by Creating Media” and hit Next.

install by creating media

Now select the Media to use, in this example I am going with USB flash drive. Make sure you have a flash drive of 4 GB or more.

flash or iSO

Select the USB flash drive you want to use and click Next.

Select USB

Next, you’ll get a message to confirm that all files on the flash drive will be deleted. Click Yes.

files deleted warning

Now, wait while the flash drive installer is created.

Creating USB

Success! The USB flash drive installer for Windows 8.1 has been created. Click Finish to close out of the wizard. You can use this to update other Windows 8 systems to 8.1 or install it on another partition if you plan to dual boot.

flash drive ready

Insert the USB flash drive you just created on a Windows 8 system and launch setup.exe.

Setup executable flash drive

When the setup wizard starts you’ll have the option to get important updates during the install – I recommend using that option so the installation goes smoother.

Get Updates

Next, you’ll need to agree to the EULA or License Terms.


Then follow the onscreen instructions to complete the installation of Windows 8.1. If you want this to be a seamless update, tick the option to keep your settings, personal files, and apps.

Choose What to Keep


When going from Windows 8 to 8.1, you can keep all of your settings and apps. Remember, if you want to upgrade from the 8.1 Preview to the final version, you’ll lose all of your apps and desktop programs — for what reason, only Microsoft knows. When installing from the Preview though, all of your modern app tiles will display, with a download arrow. So, you just need to go through and click each tile of the modern app you want to get back.

If you don’t want to create a flash drive from this wizard, at the beginning select to download the ISO file. Then you can burn it to DVD or make a USB flash drive later by following this article.

The update process got off to a rough start yesterday, so you might want to hold off updating for a few days. Just like when Apple gets a new iOS update, downloading it to your device is a long arduous process because everyone is nailing the servers at once.

There are several other upgrade paths you can take to Windows 8.1 from XP SP3, Vista, and Windows 7. I will be running tests for each of these scenarios, so make sure to check back here often.



  1. Jeevan

    October 19, 2013 at 8:30 am

    I don’t have 8.1 key but I need an ISO file…i do have a genuine 8 key…it’s not accepting to download 8.1 ISO

  2. Greg

    October 19, 2013 at 9:51 am

    Two different Product Keys from my original 8.0 installation will work when I try to start the 8.0 download, but the same keys will not work trying to download the 8.1 file. The screen asks for the Product Key from the 8.1 ‘purchase’. The whole point is to upgrade from 8.0 to 8.1 without an additional purchase.

  3. Cho

    October 19, 2013 at 3:37 pm

    Hey Brian…….Hello….

    What Jeevan & Greg said above.


  4. Brian Burgess

    October 19, 2013 at 4:55 pm

    OK. I have been having several complications with the Windows 8.1 update over the past couple of days. I have been wiping different physical machines, and working different scenarios with VMs.

    In fact, when I attempted to update my Surface RT from the 8.1 Preview…it “bricked” and I had to do a complete PC Reset back to Windows 8.

    To further complicate matters, Paul Thurrott is reporting that the 8.1 update is temporarily unavailable:

    When I went through and tried this process again, the Win8 Pro key didn’t work as you guys are reporting– so I ended up using an 8.1 key from my TechNet subscription … I know, no help for everyone there.

    I don’t understand why Microsoft wouldn’t allow people who have a valid Windows 8 product key to use it, since this is a free upgrade. Also, Microsoft is giving us the ability to download the ISO which is outlined on this Microsoft page:

    I am going to test this out further over the weekend.

    I haven’t tried the method that Ziggy points out that’s on ASKVG:

    But it sounds reasonable.

    Thanks for the heads up Ziggy! If you do have success with that please let us know.

  5. Jeevan

    October 19, 2013 at 11:15 pm

    Is there a way to download 8.1 ISO. Ziggy I have tried your link it’s showing me a error that this product key cannot be used to install a retail version of windows 8.1. My only concern is what should we do when there is a problem with my computer? Of course refresh or reset. But I shows me a error some files are missing please use recovery media. Since we don’t have a 8.1 ISO i have to install 8 again and update 8.1. Now what’s this???

  6. Jeevan

    October 20, 2013 at 2:58 am

    Ziggy…awesome…the 3rd site link you have mentioned…they have given a key for 8.1 pro and the downloader for 8.1 is accepting the key…

  7. Jeevan

    October 20, 2013 at 3:04 am

    Hey Brian…ziggy mentioned a url link…3rd one…you can see 8.1 key in that site. Can you use that key and install 8.1. Then change the product key and check whether 8.1 is activated with 8 key. I would have tried it but I live in India and it takes sometime to download ISO file… Can you check it???

  8. mur_phy

    October 20, 2013 at 2:56 pm

    I have not read all of the link above and if the solution is there this next may not be of value. Not sure how many characters are allow either but will try to publish a solution created by another of the PC Tech admins (Paltalk room).

    Using a USB stick installer allows you to start a clean 8.1 instal, but it won`t run because it did not accept my 8.0 OEM key.
    here is a link to generic keys

    This link provides info on the problem

    8.1 does not allow you to do a clean instal with a 8.0 key, but you can activate 8.1 with a 8.0 key once you are past that hurdle.
    I recommend making a USB stick installer, then go to the sources folder, in there create a .txt file with notepad with the contents:
    This is assuming you use the pro edition like me.
    Next save that file as ei.cfg in the sources folder, this makes the installer skip the key check !
    You can instal 8.1 without a key and when you are done it asks you to remove the USB stick, it reboots, and starts the OOBE.
    This asks you for a key again but this time it DOES accept your 8.0 key and activates windows.
    When you finally get a desktop you can check the system window, it will tell you Windows is activated.
    The final problem is that this gave me a non-functional 300MB recovery partition created by the installation proces, that still did not allow me to use refresh/reset, still missing files.
    The USB stick installer you create however does allow you to refresh/reset when plugged in, but this does not restore your recovery partition, but you can use the feature.
    I also really wanted to have a usable recovery partition on my harddrive, turns out making one is really simple.
    To do this create some unpartitioned space, I used 3200MB.
    In this space create a 3200MB NTFS partition, and volume, I named it 8.1 recovery but any name will do, and do a quick format.
    Next copy the contents of the ISO or the contents of your USB installer into that partition, it should leave about 87 MB free space.
    You can remove the drive letter if you like, so you can`t accidentally modify the files easily.
    Remove your USB stick or unmount the ISO and you fill find that the refresh/reset features now work :)

    hopefully that info will of value to users trying to update W8 to W8.1 via USB

  9. Greg

    October 20, 2013 at 4:38 pm

    This worked for me

    1 –
    2 – Download Win8 Installer > run > Enter Win8 Product Key
    3 – Exit this installer (not pause)
    4 – Now download Win8.1 Installer > run…………….. No key needed

    Kudos go to Philip at
    who in turn got the idea from +ViperAFK on the Neowin forums –

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