Failed promote Active Directory

Question

Failed promote Active Directory

Haza Hafiz Riski 65

I have Active Directory on Windows Server 2012. I want to migrate to Windows Server 2025, but when I 'Promote' fails because the forest function level is still Windows Server 2012. To do this, I first install the Active Directory role on Windows Server 2019, then demote Active Directory on Windows Server 2012. After that, I try to 'Promote' again, but it still fails with the same error.
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Answer 1

Jason Nguyen Tran 12,715 Independent Advisor

Hi Haza Hafiz Riski,

I’m following up to check whether the issue has been resolved. Feel free to reply if you need further information. If the information provided was helpful, please click "Accept Answer" to help others in the community. Thank you!

Haza Hafiz Riski 65 Reputation points

2026-03-05T08:14:27.7433333+00:00

Hi Jason,

I have already demoted and unjoined the domain in Windows Server 2012, but as shown in the previous image (from Windows Server 2019), the option to upgrade to Windows Server 2016 is still not available.

Haza
Jason Nguyen Tran 12,715 Reputation points Independent Advisor

2026-03-05T08:20:48.4333333+00:00

The reason you still don’t see the option to raise the forest functional level to Windows Server 2016 is that the forest still contains one or more domain controllers that are not yet running Windows Server 2016 or higher. Even if the 2012 DC was demoted, the forest functional level cannot be raised until all domain controllers across the forest are upgraded to at least 2016.

I recommend verifying the current domain controllers in your forest. You can do this by running nltest /dclist:<domainname> or checking Active Directory Sites and Services. If any domain controllers are still running 2012, they must be removed or upgraded. Once every DC is at 2016, 2019, or 2022, you can raise the domain functional level first (via Active Directory Domains and Trusts or PowerShell), and then raise the forest functional level.

Only after both levels are raised to at least Windows Server 2016 will you be able to successfully promote a Windows Server 2022 or 2025 domain controller. This requirement is enforced by design to ensure compatibility and stability across the forest.

Answer 2

Jason Nguyen Tran 12,715 Independent Advisor

Hi Haza Hafiz Riski,

Based on your screenshot, the error is tied to the forest functional level. Windows Server 2025 requires the forest functional level to be at least Windows Server 2016, so if your forest is still at 2012, promotion will fail regardless of the intermediate steps you’ve taken.

The preferred approach is to raise the forest and domain functional levels before attempting to promote a new domain controller. You can do this from Active Directory Domains and Trusts or via PowerShell, but keep in mind that all domain controllers in the forest must be running at least Windows Server 2016 before you can raise the level. That means you’ll need to upgrade or replace any remaining 2012 domain controllers first.

Once all domain controllers are on 2016 or higher, raise the domain functional level, then the forest functional level. After that, you should be able to successfully promote a Windows Server 2025 domain controller. If you’ve already installed a 2019 DC, that’s a good step forward, just make sure you demote the 2012 DCs and then raise the levels accordingly.

I hope the response provided some helpful insight. If it clarified the issue for you, please consider marking it as Accept Answer so others with the same issue can find the solution.

Jason.

Haza Hafiz Riski 65 Reputation points

2026-03-03T07:16:57.2966667+00:00

Yes, I realize that the minimum forest functional level in Windows Server 2025 is Windows Server 2016. I have already demote Active Directory in Windows Server 2012, but I still cannot upgrade the forest functional level to Windows Server 2016:

Haza
Jason Nguyen Tran 12,715 Reputation points Independent Advisor

2026-03-03T07:30:29.02+00:00
The reason you still cannot raise the forest functional level is that the forest contains one or more domain controllers that are not yet running Windows Server 2016 or higher. Even if the 2012 DC was demoted, the forest functional level cannot be raised until all remaining domain controllers across the forest are upgraded to at least 2016.

Here’s the step‑by‑step path forward:

Verify that every domain controller in the forest is running Windows Server 2016, 2019, or 2022. If any are still on 2012, they must be upgraded or removed.

Once all DCs are compliant, open Active Directory Domains and Trusts and raise the domain functional level to Windows Server 2016.

After the domain level is raised, raise the forest functional level to Windows Server 2016.

Confirm replication is healthy across all DCs before attempting promotion.

At that point, you should be able to promote your Windows Server 2025 domain controller successfully.

I hope this clears up why the upgrade is blocked and helps you move forward with your migration. If you find this answer helpful, please consider clicking Accept Answer so others can benefit too.

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Failed promote Active Directory

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