The new Windows Server 2025 brings some new features for the Active Directory and also makes the upgrade particularly easy. An inplace upgrade to Windows Server 2025 is possible from Windows Server 2012 R2 without an intermediate step. In principle, only the Server 2025 ISO needs to be mounted and it can be upgraded directly.
In this article, I will go through the Inplace Upgrade from Windows Server 2022 to Windows Server 2025:
The Active Directory with the name "frankysweblab.de" is still running with the overall structure and domain function level "Windows Server 2016", under Windows Server 2022 this is the highest function level:
To upgrade a domain controller to Windows Server 2025, the Active Directory schema must first be updated. The Inplace Upgrade does not perform this step automatically. To perform the schema update, the Windows Server 2025 ISO must first be mounted. You can then switch to the corresponding drive in the CMD, in my case it is D:\. The preparation of the overall structure and the domain is then completed in two simple steps. The following command updates the forest schema:
D:
cd support/adprep
adprep /forestprep
The domain is updated with the following command:
adprep /domainprep
In principle, this is all the preparations you need to make. However, before starting the setup from the ISO, you should check once again whether other software is installed on the domain controller, for example virus scanners or any management agents. To be on the safe side, I would uninstall this software before the inplace upgrade and install the current and compatible versions after the upgrade.
The setup can now be started directly from the ISO:
The next steps can be confirmed with "Next, Next Next":
Since Windows Server 2025 requires a new license and product key, this can be entered directly:
The version to be installed must match the product key:
...Next...
Normally there is not much to take over on a domain controller:
...Next...
Last confirmation before the inplace upgrade:
The inplace upgrade is now performed and the server is automatically restarted several times:
The display changes from time to time:
After a while, it took me about 30 minutes, the Inplace upgrade is complete:
After the inplace upgrade, the available Windows updates can now be installed:
If all domain controllers of the overall structure have been updated to Windows Server 2025, the overall structure and domain functional level can also be raised to "Windows Server 2025". The function level can be raised via the MMC console "Active Directory Domains and Trusts":
The domain function level can now be raised to Windows Server 2025:
The same applies to the overall structure function level:
All new Active Directory features of Windows Server 2025 will only be available once the function levels have been updated. There will be another article on the new AD features soon.