AD functional level upgrade planning
Microsoft's edit ·
Microsoft's commit message in MicrosoftDocs/windowsserverdocs · commit 655632e · +19 −19 lines · also on GitHub
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- New Windows Server 2008 R2 forest
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−- Windows Server 2016 forest to Windows Server 2022 or Windows Server 2025 (preview)
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+- Windows Server 2016 forest to Windows Server 2022 or Windows Server 2025 (preview)
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+## Upgrading functional levels to Windows Server 2025 (preview)
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+Functional level upgrade for Windows Server 2025 (preview) includes the following requirements:
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+- For new Active Directory forests, the minimum functional level must be set to Server 2016.
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+- Existing domains must be at least at the 2016 functional level to promote a Windows Server 2025 to a domain controller.
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+Upgrade methods include the following options:
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+- Set up a new Active Directory domain with the new Domain Functional Level (DFL) and Forest Functional Level (FFL) when promoting the first Domain Controller for the new domain
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+- Install Active Directory Domain Services on the new Windows Server to automatically run adprep on the previous version forest and domain
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+ > [!IMPORTANT]
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+ > A Windows Server 2025 (preview) domain controller can only be added to an existing domain that is running Windows Server 2016 Domain Functional Level or newer version. You must also ensure that all hardware and software requirements for Windows Server 2025 (preview) are met.
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## Upgrading functional levels in a Windows 2016 Active Directory forest
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In a Windows 2016 native environment that consists only of Windows 2016-based domain controllers, the functional levels are set by default to the following levels, and they remain at these levels until you raise them manually:
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- Windows 2016 forest functional level
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−In addition, the follow must be true prior to upgrade:
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+In addition, the following must be true prior to upgrade:
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- All domain controllers must be running Windows Server 2016, Windows Server 2019, or Windows Server 2022.
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> [!IMPORTANT]
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> You must check for deprecated features prior to upgrade to make certain that none are being used. Also verify that all domain controllers are correctly replicated both before and after the upgrade.
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−### Upgrading functional levels to Windows Server 2025 (preview)
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−Functional level upgrade for Windows Server 2025 (preview) includes the following requirements:
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−- For new Active Directory forests, the minimum functional level must be set to Server 2016.
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−- Existing domains must be at least at the 2016 functional level to promote a Windows Server 2025 to a domain controller.
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−Upgrade methods include the following options:
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−- Set up a new Active Directory domain with the new Domain Functional Level (DFL) and Forest Functional Level (FFL) when promoting the first Domain Controller for the new domain
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−- Install Active Directory Domain Services on the new Windows Server to automatically run adprep on the previous version forest and domain
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− > [!IMPORTANT]
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− > A Windows Server 2025 (preview) domain controller can only be added to an existing domain that is running Windows Server 2016 Domain Functional Level or newer version. You must also ensure that all hardware and software requirements for Windows Server 2025 (preview) are met.
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## Upgrading functional levels in a native Windows 2000 Active Directory forest
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Microsoft's Markdown source from MicrosoftDocs/windowsserverdocs, © Microsoft Corporation, under CC BY 4.0. Changed lines with up to 3 unchanged lines around each; ChangeIntel kept this copy 10 Oct 07:36 UTC. The commit date is when the source changed, which can be hours or days before Learn published it.