Forum Discussion
Side-by-side Upgrade: Server 2012 R2 Foundation to Server 2025 Essentials
Hello,
A direct side-by-side upgrade from Windows Server 2012 R2 Foundation (running as a Domain Controller) to Windows Server 2025 Essentials is not supported as an in-place upgrade path, and there are also important edition limitations to consider.
Key Points
Edition Limitation (Critical)
Foundation edition has strict limitations (e.g., max 15 users, limited roles).
It cannot be directly upgraded to newer editions like Essentials or Standard.
Microsoft does not provide a supported in-place upgrade path from Foundation → newer versions.
Recommended Approach: Side-by-Side Migration (Supported Method)
What is supported is a migration, not an upgrade:
✔️ Build a new server with Windows Server 2025 Essentials
✔️ Join it to the existing domain
✔️ Promote it to Domain Controller
✔️ Transfer FSMO roles
✔️ Migrate services (DNS, DHCP, File Shares, etc.)
✔️ Demote and decommission the old 2012 R2 DC
Domain Functional Level
Ensure your current domain functional level (likely 2012 R2) is compatible.
After migration, you may optionally raise the functional level.
Essentials Edition Consideration
Essentials has its own limitations (user/device caps, simplified management model).
Make sure it fits your production needs—otherwise consider Standard edition.
🛠️ High-Level Migration Steps
Install Windows Server 2025 Essentials
Configure IP & DNS pointing to existing DC
Join domain
Install AD DS role
Promote to Domain Controller
Transfer FSMO roles:
Move-ADDirectoryServerOperationMasterRole -Identity "NEWDC" -OperationMasterRole 0,1,2,3,4
Verify replication:
repadmin /replsummary
Migrate additional roles (DNS/DHCP/File Services)
Demote old DC:
Uninstall-ADDSDomainController
Thanks, kyazaferr, for your reply.
Does it make sense to migrate to an intermediate Server 2019, that is, to first migrate Server 2012 R2 to Server 2019 and then Server 2019 to Server 2025?
It does not actually. You can migrate straight to a new version. Just be careful about the April update which enforce by default the AES encryption by default.
Good luck .
Thanks Mister_K for yor reply.
I'm asking because when i try to promote ther Server 2025 to Domain Controller it's says "Verification of replica failed. The forest functional level is not supported. To install a Windows Server 2025 domain or domain controller, the forest functional level must be Windows Server 2016 or higher."
Hello ,
Indeed, there's a requirement : You need at least to have a functional level at 2016 to integrate a 2025 WS domain controller . You have to promote the forest functional level first. Then, promote your Windows Server (WS) 2025 as a Domain Controller.
Before to raise the functional level, audit your Active Directory and the objects (applications, etc etc...) to make sure , it will be fine.
Best.
