Why Your Windows Installation Is Not Genuine (and What You Can Do About It)

While using a Windows operating system, you may be plagued with a message that states your Windows is “not genuine.” If you’re using older versions of Windows, the desktop may turn black, a small message at the bottom-right will warn you that it’s not genuine, and you’ll be locked out of viewing the system’s properties. In this case you might be interested in how to fix Windows’ not genuine errors. If this happens to you, there are a few reasons this could have happened.

  1. You’re using a copy of Windows that you downloaded off the Internet for free.
  2. You bought a PC or Windows product key from a seller, and the error message has appeared since first boot.
  3. You bought and used a genuine copy of Windows, but it suddenly claimed it’s not genuine.
  4. The computer’s hardware changed in some way.

Fixing the “Windows is not genuine” error depends on which of the above categories you fall into.

1. If you downloaded Windows off the Internet

One way to get this error message is if you managed to download a copy of Windows off of the Internet without paying. You may have seen an article or a link advertising you can get a Windows operating system “for free,” and liked the sound of it. Unfortunately, while a free copy of Windows does sound great, this is, unfortunately, software piracy!

As of this writing, there’s no legitimate and legal way outside of student plans to download and install a Windows operating system for free. Any methods claiming you can do so are illegal, and as such, the copy of Windows you downloaded is claiming it’s “not genuine” because you didn’t pay for it. This is akin to when people download movies, CDs, and games off the Internet for free. As such, this is not an ideal situation to be in.

What do I do?

If you’re in this situation, what paths of action can you take to rectify it?


For one, it’s still not too late to purchase a legitimate copy of Windows. You can buy the operating system either as a disk from your favourite computer store or as a download or license through the Microsoft store. Once bought, you can use the license to validate your copy of Windows. This will fix Windows’ not genuine messages for good.

Unfortunately, Windows keys don’t come very cheap; they usually sell for around $100-$200. If you need an operating system for your computer but don’t have the money for one, you can always try Linux instead. Linux operating systems are available to legally download free of charge, so you can use them without being hassled for money. You can read our beginner’s guide to Linux distros to get an understanding of what they can offer you.

If you’re using an operating system older than Windows 10, you may be able to rearm the license so you can continue to use it. To do this, open a command prompt and type slmgr -rearm in it. Be warned, however – this will only reactivate Windows for 30 days, and you can only do it three times, so use this only as a temporary solution to fix Windows’ not genuine messages while you get a more permanent fix sorted.

2. If you bought a computer or key with the error message

Sometimes, however, you purchase a computer legally with the promise that it comes with Windows, or you buy a Windows key from a key dealer. When you use it, you find out that Windows is marked as not genuine. This is particularly harsh, as you’ve gone out of your way to buy a copy of Windows, only to find that it’s counterfeit.

What do I do?

First, contact those who sold you the computer or key. Hopefully there was just a mistake within the transaction, and the person who sold you the product will take the steps necessary to rectify the problem.

If, however, you believe they may have intentionally sold you a counterfeit copy of Windows, you can report them using the Windows Piracy Reporting website. Microsoft will investigate your case and check to see if the person you bought it from is selling counterfeit computers. If you purchased the product using PayPal (such as on eBay), you can refute the purchase within forty-five days of buying it and get your money back.

3. If your copy of Windows was genuine but suddenly changed

Sometimes, a copy of Windows you know is genuine suddenly claims it’s not. If this sounds like you, first make sure that you have not changed any hardware within your PC. If you have, skip to the section below which may suit your needs better. Otherwise, see if the following tips manage to fix Windows’ not genuine errors.

What do I do?

First of all, checking the license can fix Windows’ not genuine errors. You can check it by right-clicking My PC and clicking “Properties,” then checking the “Windows activation” box at the bottom.



Sometimes it’ll let you know whats wrong with the license so you can fix it. Sometimes simply checking this screen then resetting your PC can fix any glitches in the licensing system.

If this doesn’t work, check if the Plug and Play policy is interrupting your licensing. Microsoft has detailed the steps you need to take to fix this here.

In some cases the result of a virus infecting your computer can corrupt the licensing. Make sure your computer is virus- and malware-free by running your favourite antivirus on your PC. Hopefully, if any viruses are found and removed, removing them should fix the issue.

If this doesn’t work, your best bet is probably re-activating your PC. Locate your Windows product key (and if you can’t, we have your back!) then either go through the official activation process or call Microsoft support and let them know of your predicament.

4. If you changed the hardware in your PC


Sometimes after you’ve changed a key component within your computer, you’ll be greeted with a “Windows is not genuine” error message, despite the fact that it was genuine before. What has probably happened here is that your PC’s Windows key was an OEM (Original Equipment Manufacturer) key. These keys aren’t like regular retail keys, as they’re only valid for the PC they’re installed on. As a result, they’re cheaper for computer manufacturers to use. As soon as the license detects it has changed computers, the key is invalid. Given you’ve changed the internal hardware within the PC, your license thinks it’s on a different computer and becomes invalid.

What do I do?

First of all, you need to ask yourself if you will you be changing your hardware frequently. If so, you may want to consider purchasing a retail copy of Windows instead. This allows you to modify the hardware within your PC without the license expiring.

If you’d rather not shell out for a copy of Windows, don’t fret just yet. You can call Microsoft support and let them know what happened and what you changed on your PC. If they deem your case as valid, they’ll help you reactivate your copy of Windows.

If you’re using Windows 10, you can avoid having to call customer support next time by linking your license to your Microsoft account. Then, when you change hardware and Windows gives its error, you can fix it with the click of a few buttons. Of course, you need to link your license before you change your hardware! Make sure to read Microsoft’s guide on the topic so you don’t have to go through this again.


As much as the “Windows is not genuine” error sounds like the operating system was pirated, sometimes a well-meaning or even legitimate user will see this error pop up. Now you know how to tackle and fix Windows’ not genuine errors should they appear for you.

Have you ever had a copy of Windows that either wasn’t genuine or claimed that it wasn’t? Let us know your stories (and fixes!) below.

Simon Batt
Simon Batt

Simon Batt is a Computer Science graduate with a passion for cybersecurity.

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