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Windows MAK keys are volume license. &nbsp;Volume license is Enterprise only. &nbsp;You cannot cross from non-Enterprise to Enterprise on the upgrade paths.<br />
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8/8.1 upgrade path info can be found here: <a href="https://technet.microsoft.com/en-GB/library/jj203353.aspx" rel="ugc">https://technet.microsoft.com/en-GB/library/jj203353.aspx</a><br />
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This also doesn't take in to account that upgrading from OEM to retail is also often not supported by MS, and then again adding edition changes back in to the equation. &nbsp;Looks like a clean install for you methinks.<br />
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The most pertinent part of the link:<br />
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<b>&quot;Upgrade to Windows 8 Enterprise (Volume License)<br />
You can upgrade to Windows 8 Enterprise (Volume License) from the following operating system editions:<br />
Windows 7 Professional (Volume License) <br />
<br />
Windows 7 Enterprise (Volume License)<br />
<br />
Windows 8 (Volume License)&quot;</b>
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No, MAK are not enterprise only, but also the pro edition can be aquired using a volume license (we do this) and with it comes a MAK key that you can use with any 8.1 pro setup ISO that I have encountered, so far.
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My organisation has quite a number of computers running Windows 8.1 SL (OEM) as it came installed when purchasing the machine. We have recently purchased a Volume License (MAK) Key in order to upgrade these computers to Window 8.1 Pro.<br />
I click on &quot;Get more features with a new edition of Windows&quot; and enter the new MAK key and get the following message: &nbsp;&quot;This Key won't work. Check again or try a different key&quot;<br />
<br />
I have found a way to get our Windows 10 SL machines to work but that method does not work with Windows 8.1<br />
We also have Windows 7 computers that I will need to do the same with.<br />
<br />
How can I get this to work as I do not want to have to reinstall all these computers?<br />
<br />
Thanks
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My organisation has quite a number of computers running Windows 8.1 SL (OEM) as it came installed when purchasing the machine. We have recently purchased a Volume License (MAK) Key in order to upgrade these computers to Window 8.1 Pro.
I click on "Get more features with a new edition of Windows" and enter the new MAK key and get the following message:  "This Key won't work. Check again or try a different key"

I have found a way to get our Windows 10 SL machines to work but that method does not work with Windows 8.1
We also have Windows 7 computers that I will need to do the same with.

How can I get this to work as I do not want to have to reinstall all these computers?

Thanks

Upgrade Windows 8.1 SL (OEM) to Pro using MAK key

Windows 8 is a personal computer operating system developed by Microsoft as part of the Windows NT family of operating systems, with an emphasis on improving its user experience on tablets. In particular, these changes included a touch-optimized Windows shell based on Microsoft's "Metro" design language, the Start screen, a new platform for developing apps with an emphasis on touchscreen input, integration with online services, support for USB 3.0, Advanced Format hard drives, near field communications, and cloud computing. Additional security features were introduced, such as built-in antivirus software, integration with Microsoft SmartScreen phishing filtering service and support for UEFI Secure Boot on supported devices with UEFI firmware.

Windows 8

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