Solved: How do I fix “Active Directory on this domain controller does not contain” in-place upgrade error Windows Server 2016 Domain Controller to Windows Server 2019?

Problem Symptom: User reported that Windows Server 2016 take a very long time to perform an in-place upgrade to Windows Server 2019. Insert the ISO installation media and follow the instructions to perform an in-place upgrade, enter the product key when prompted. Domain controller in-place upgrade warning is prompted.

The detailed error message is as below:

What needs your attention
The following things need your attention to continue the installation and keep your Windows settings, personal files, and apps.
Change what to keep
Active Directory on this domain controller does not contain Windows Server 2019 ADPREP / FORESTPREP updates

Active Directory on this domain controller does not contain Windows Server 2019 ADPREP / FORESTPREP updates

Follow the below solution steps to resolve “Active Directory on this domain controller does not contain” in-place upgrade error.

Content Summary

Potential Causes
Pre-check
Solution

Potential Causes

There’s only one server in the domain which the schema has not been updated for 2019 domain controllers.

Pre-check

Warning: check your hardware, Hypervisor support, and all the installed applications support the version of Windows Server 2019. Backup and snapshot before proceed.

Solution

Step 1: Do not close the Windows Server 2019 Setup windows.

Step 2: Open Command Prompt and run it as administrator (in elevated mode).

Step 3: Change to the D:\Sources\Adprep directory

Step 4: Execute the following command to upgrade the forest schema: adprep.exe /forestprep

Step 5: Press C and then Enter key to continue.

Execute the following command: adprep.exe /forestprep

Step 6: Execute the following command to update the domain wide information: adprep.exe /domainprep

Execute the following command: adprep.exe /domainprep

Step 7: Close the command window.

Step 8: Switch back to the Windows Server 2019 Setup windows, and continue the upgrade process.

Step 9: The server will reboot and upgrade.