Running AD Schema Update for 2008 R2 in a 32-bit DC Environment

To upgrade Active Directory from Windows Server 2003 to Windows Server 2008 R2 requires the usual AD schema upgrade first of all. Windows Server 2008 R2 is 64-bit only, so if you try running the usual command to upgrade the schema from a 32-bit Domain Controller:

adprep /forestprep

you get the following result, “adprep.exe is valid, but if for a machine type other than the current machine.”:

An alternative is to try running it from a 64-bit machine that is not a DC, but then you discover that this process absolutely must be run from a DC:

So what do you do? The answer is that you run adprep32.exe, a 32-bit version of adprep, which is included in the same folder:

adprep32 /forestprep