Friday, April 22, 2011

Error Adding Windows 2008 R2 to Existing 2003 Active Directory

Tonight I'm trying to promote a spanking new Windows 2008 R2 server as a domain controller in an existing Windows 2003 AD.  When I ran dcpromo on the new server I was presented with the following message from the Active Directory Domain Services Installation Wizard, "To install a domain controller into this Active Directory forest, you must first prepare the forest using "adprep /forestprep".  The Adprep utility is available on the Windows Server 2008 R2 installation media in the \support\adprep folder."

I promptly opened and Command Prompt on the R2 server, navigated to the \support\adprep folder and ran adprep /forestprep.  No joy!  Now I got the message:
Adprep cannot run on this platform because it is not an Active Directory Domain Controller.
Adprep stopped without making any changes.
[User Action]
Run Adprep on a Active Directory Domain Controller.
So, I went to one of my 2003 domain controllers and ran adprep /forestprep.  Another problem!
The image file C:\support\adprep\adprep.exe is valid, but is for a machine type other than the current machine.
It took a few minutes but I finally figured out I need to run adprep32 /forestprep since my 2003 server is 32 bit.  Ah, hah!  Of course, there's this little message:
Before running adprep, all Windows 2000 Active Directory Domain Controllers in the forest should be upgraded to Windows 2000 Service Pack 4 (SP4) or later.
[User Action]
If ALL your existing Windows 2000 Active Directory Domain Controllers meet this requirement, type C and then press ENTER to continue. Otherwise, type any other key and press ENTER to quit.

Just a little bit more....

From the same 2003 server you'll have to run adprep32 /domainprep as well.

Now that adprep(32) /forestprep  and adprep(32) /domainprep were successfull I can promote my 2008 R2 server to DC.


  1. Thanks, i had the same problem, first i run adprep in win 2008 r2 32bit disk, it works but when I run dcpromo in windows 2008 it was not able to promote. Then I try adprep32 in win 2008 r2 64bit disk after that I can dcpromo the 2008 r2 machine

  2. Thanks for your clear tutorial

  3. Thank's a lot...i have the same problem also, now it's solve. Thank's...

  4. Thank u so much ...it is working fine