Question : Error running DC Promo on Windows 2008 R2

I am trying to DC promo a second DC running Windows 2008 R2 in a domain with an existing Windows 20008 but getting the error: The procedure entry point I_NetPathType could not be located in the dynamic link library NETAPI32.dll

Answer : Error running DC Promo on Windows 2008 R2

You need to run adprep on the primary Windows Server 2008 domain controller machine to update your infrastructure to the 2008 R2 directory schema/forest. The proper adprep tools are located on your Windows Server 2008 R2 installation disc. Run adprep and then domainprep.

http://technet.microsoft.com/en-us/library/cc771433(WS.10).aspx#BKMK_NewDCScenario