Sorry to say, backup and restore or copying the DHCP folder from the windows 2003 to windows 2008 wont work anymore as it did. why is that ? because of the format change between the versions.

The recommended procedure for DHCP server migration is to use the export and import commands (netsh). The procedure for migrating DHCP server from Windows Server 2003 to Windows Server 2008:

Export the DHCP database from the server that is running Microsoft Windows Server 2003: start -> run -> cmd. type the following command – netsh dhcp server export C:\<somefilename>.dat all

note: while exporting the database, the DHCP server service will stop until the process finish.

On the destination server (the windows 2008\R2) install the DHCP role, don’t take your time in configuring the DHCP role because we’ll remove the configuration : server manager -> add roles -> dhcp server

Very important note :On the new installed DHCP server remove any option an configuration that the wizard has created, if you wont do that, the import process will fail.

Import the DHCP database (on the destination server) : copy the dat file from the windows 2003 server to the destination server and import it : start -> run -> cmd. type the following command – netsh dhcp server import C:\<somefilename>.dat all

if you installed the DHCP on Domain Controller, after successful import of the database check if the server already authorized, if it is – Unauthorized it and Authorize again. check in ADSIEDIT.msc that your new DHCP is really authorized : expand the CN=NetServices,CN=Services,CN=Configuration,DC=domain,DC=local and locate the server with the DhcpRoot object type. restart the server and check that the DHCP service is in started mode, if not it probably because its not authorized (you may see events for this issue in the event viewer – event 1046), if its unauthorized try to restart the service. if it worked its because the DHCP server tried to verify the DhcpRoot object for the server in the Active Directory before the NTDS service has started, to solve that, add dependency to the DHCP server service  :

1. start -> run -> regedit
2. navigate to HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\DHCP
3. locate the DependOnService key and append to it the word : NTDS (if it doesn’t exists create one with type of REG_MULTI_SZ)
4. close the regedit
5. restart the server to check it solved the problem.