Hello,
It's really up to you to get a downgrade key. You have the rights to downgrade bu you may have to supply the media and keys to do so.
Normally Microsoft only supplies N-1 media and keys from the Microsoft 365 Portal.
Check this page:
Darrell
No option to downgrade Windows 10 LTSC 2021 to LTSC 2015
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CK Cheng
25
Reputation points
Hi all,
I need a Windows 10 LTSC 2015 license for a system which the existing RAID hard disk failed, and I do not have the license key backup.
Refer to previous post as follow, I would be able to downgrade the LTSC 2021 to LTSC 2015. However, after getting the LTSC 2021 license, the downgrade options available in the Microsoft 365 admin are only down to LTSC 2019. Can anyone advise how can I get the LTSC 2015 license key?
The SKU for the software purchased is DG7GMGF0D19L.
Thanks.
Windows for business | Windows Client for IT Pros | Devices and deployment | Recovery key
2 answers
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Darrell Gorter 2,901 Reputation points2025-08-13T21:44:20.09+00:00 -
CK Cheng 25 Reputation points
2025-08-14T03:03:53.4633333+00:00 Hi,
Thanks for the reply. As per the Licensing Downgrade brief, it is confirmed that I can downgrade to previous version.
Licensing_brief_PLT_Downgrade_Rights.pdf
As per my earlier post, I can only access to license key of N and N-1.
So, I still unable to get the license key to activate the previous version. There will be a watermark stated the Windows is not activated. Therefore question is:
- Is there any way to get the license key to activate the previous version?
Thanks.
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Darrell Gorter 2,901 Reputation points
2025-08-14T05:08:30.08+00:00 Hello,
Did you see this line in the article:
"With downgrade rights, you can install and use any earlier version or a permitted edition in place of the licensed product. However, Microsoft does not provide installation media or product keys for older versions."
It's up to you to supply the license key that you need.
Darrell
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Domic Vo 8,375 Reputation points Independent Advisor2025-08-14T11:21:20.7366667+00:00 Dear CK Cheng,
Microsoft Volume Licensing customers are entitled to downgrade rights, which allow installation of earlier versions of Windows in place of the licensed product. However, as noted in our Downgrade Rights Licensing Brief, Microsoft does not provide installation media or product keys for older versions such as LTSC 2015.
This means that while you are permitted to install LTSC 2015 under your LTSC 2021 license, you will need to supply the installation media and product key independently. The Microsoft 365 Admin Center typically only provides access to the current version (N) and the previous version (N–1), which in this case is LTSC 2019.
- Check with your original license provider or IT administrator to see if the LTSC 2015 key was archived or backed up elsewhere.
Review any previous activation records or emails that may contain the key.
If your organization uses Key Management Services (KMS), verify whether the LTSC 2015 key was registered with your KMS host. You can find guidance on KMS activation here.
If no recovery is possible, you may need to consider using LTSC 2019 or LTSC 2021, depending on compatibility requirements.
I hope this helps,
Best regards,
Domic Vo