Hello,
I wanted to check and see if I missed anything from my checklist that will be used for upgrading DCs from 2003 to 2012. Please let me know. DCs will be installed on the new hardware and new VMs (VMware)
• New member server 2012 R2
• Add DNS role and promote to DC
• Verify the replication was successful and that the server is working
• Change client and non-DC servers DNS to point to the new 2012 server
• Verify that clients and non-DC servers are working without any issues with 2012 server
Your Forest and Domain Functional levels should be Windows Server 2003. Please check that.
Whenever you are installing a DC with new OS, schema will be updated. This step is included in the ADDS configuration wizard and will require privileges of Schema Admin. Also you will require Enterprise Admin privileges for DC installation. So, please confirm the account you use is member of groups Enterprise Admins and Schema Admins.