Upgrade from a domain controller that is Windows 2008 SP2 to Windows 2008 r2

I had to do a 'simple' upgrade of a domain controller from SP2 to R2...easy right? Sure, if you know how.

Follow these steps:

1. Make sure you are going from x64 to x64. If you are trying to go from 32-bit to 64-bit, no dice.
2. Make sure you have plenty of space on the C partition. If you have less than 10gb(rough estimate), you need to extend the partition. That is a whole other conversation but get that done.
3. From the R2 disk/iso, you need to run the following command(the path may be different from yours depending on if it's from a custom built R2 disk or not):
• D:\support\adprep\adprep /forestprep
• Press C and enter

• Reboot the server
• From the R2 disk, run the setup.exe file and go the 'upgrade' route. Accept the defaults

 Sounds simple until you do it. :)