I downloaded Windows Media Creation Tool yesterday and followed the instructions for creation a standard Windows 10 64-Bit ISO. The media was created successfully (it must have been right? The "Validation" that took a half hour or so didn't report any errors) and resides on my hard drive (not on a USB stick or a burned DVD).

Having successfully created my Windows 10 install media file, and following this tutorial (https://www.linkedin.com/learning/learning-virtualbox-2/installing-windows-10-in-virtualbox), I attempted to install Windows 10 on VirtualBox. The installer launches and I can choose my language, but when I click "setup" I immediately get the following error:

Install Windows

Windows could not load required file WinSetup.dll. The file may be corrupt. To install Windows, restart the installation.

Error code: 0xC1

I researched about the error online, but didn't find any solutions. Here are some of the interesting notes I gathered:

Reddit wonders why Windows Media Creation Tool doesn't work

Now, it took forever for the media to download, build, and verify (even with 100 Mb high speed internet) and I rather not go through that process again just to troubleshoot.


Host: Windows 10 Home 64-bit


  1. Is there a known issue with Windows Media Creation Tool not working correctly? I've seen stuff online that hint at this, but no full blown articles declaring that WMCT is faulty.

  2. What exactly is causing this error and how do I fix it? Strangely, I've found the following advice on several forums:

Try a different USB drive, or grab an ISO from here and use Rufus to create the USB drive



a. Is that site even trustworthy?

  • Any link on the unofficial official question on where to find Windows 10 ISOs are safe. “Is there a known issue with Windows Media Creation Tool not working correctly?” - No, there isn’t an issue
    – Ramhound
    Commented Mar 27, 2021 at 13:05

2 Answers 2


Microsoft wants users to use the Media Creation Tool instead to download and create installation media on a system running a supported operating system. This does not take into account situations where users may not be able to run the program, or are looking for an older version. Microsoft makes it very difficult (on purpose) to download any version but the latest one.

Adguard is a third-party web service that allows you to download Microsoft Windows and Microsoft Office ISO images. The images are downloaded directly from the Microsoft servers.

Adguard is totally safe and is used by many users and MVPs. I have already recommended it several times on our website for people looking to download a specific version of Windows or Office. All these versions would need a valid Microsoft serial or digital entitlement to be used as non-trial, which makes the download completely legal.

You have nothing to worry about by downloading from that site.


a. Is that site even trustworthy?

Rufus developer here. https://rufus.ie is the official website for Rufus, so, yes, that site is trustworthy. Or you can pick the Rufus executable (which is digitally signed by the way to confirm its authenticity) off the Open Source project on GitHub. You may also want to see our comprehensive page highlighting the security measures that are taken by Rufus to ensure that YOU can trust that it is both legit and won't try to do anything nefarious behind your back here.

Oh and if you have Rufus, then you don't need to download the ISO from adguard.net as Rufus allows you to download the retail Windows 10 ISOs (from the official Microsoft servers, i.e. the exact same images as what you'll get from Microsoft) through its ISO download feature.

Finally, once you have downloaded the ISO, and in order to make sure that it's not a problem with corrupted data (which may be the reason why MCT fails), you probably want to follow these steps to validate that the ISO you got is both retail and not corrupted.

  • Hey, thanks for chiming in! I didn't mean to imply that Rufus might be untrustworthy -- I've used it before to make a flash drive install for Ubuntu and it worked great. I only included the link for completion sake, so anyone wanting to try out the advice wouldn't only have part of the instructions. My question was actually about that Adguard site. Commented Mar 27, 2021 at 17:07
  • To clarify though, I know that Rufus make flash drives into OS install media. But, can it make an ISO on my desktop that I can use to create a virtual machine? That's what I'm really trying to accomplish. Thanks! Commented Mar 27, 2021 at 17:08
  • Rufus can not create an ISO from an existing USB driver, but it can do the next best thing, which is create a VHD copy of your USB, which can you can then use to recreate the media in exactly the same way as it was when you created the VHD. Oh, and (uncompressed) VHDs, such as the ones created by Rufus, can also be used with dd on Linux to recreate a drive. See github.com/pbatard/rufus/wiki/….
    – Akeo
    Commented Mar 27, 2021 at 20:02

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