Can Windows 2012r2 child domains be migrated to windows 2019 server keeping parent domain in windows 2012r2

Question

I have multi domain setup, where my Parent domains (primary and backup) are in Windows 2012R2 and child domains (primary and backup) are in Windows 2012R2.

Now i would like to migrate the child domains from windows 2012R2 to Windows 2019 server. Parent domains will not be migrated.

Do i face any issues since Parent domain is in Windows 2012 R2?

Answer 1

No problem. Windows Server 2019 servers can be members of 2012 R2 domains.

https://learn.microsoft.com/en-us/windows-server/identity/ad-ds/active-directory-functional-levels provides information on mixing versions.

Answer 2

I continued with Migration, and stuck while promoting the Windows 2019 server. Below is the error/warning at preparation operation stage.

Below are the steps i performed:

Given:: Multi-Domain set up

1. Parent Domain in windows 2012 R2 OS (say PATDC01)
2. Primary Child Domain in Windows 2012 R2 OS (CHDC01) and backup child domain in Windows 2012 R2 OS (say CHDC02)

When:

1. Installed Windows 2019 OS machine (say CHDC03) and added to child domain as a member.
2. Logged into the Windows 2019 server (CHDC03) as domain administrator.
3. Now promoting the Windows 2019 OS machine (CHDC03) as domain controller for child Domain.

Then:

1. below error observed

" To install this domain controller, the wizard needs to perform the following operation(s):
Forest and schema preparation
Domain preparation
The current user credentials do not have sufficient permissions to run the preparation operation(s). please specify a user that is a member of Enterprise Admins
group and Schema Admins group. "

Please suggest what needs to be done. Thanks in Advance.

Answer 3

There are some prerequisites that must be completed before adding your first 2019 domain controller. See https://learn.microsoft.com/en-us/answers/questions/66480/adding-a-2019-server-domain-controller.html#:~:text=For%20add%20a%202019%20domain%20controller%2C%20the%20steps,server%202019%20as%20a%20DC%20%28as%20a%20GC%29. for more information.

The two prerequisites to introducing the first 2019 domain controller are that domain functional level needs to be 2008 or higher and older sysvol FRS replication needs to have been migrated to DFSR
https://techcommunity.microsoft.com/t5/Storage-at-Microsoft/Streamlined-Migration-of-FRS-to-DFSR-SYSVOL/ba-p/425405