The below error may occur when running the Group Policy Modeling Report:
"System.DirectoryServices.DirectoryServicesCOMException (0x8007202B): A referral was returned from the server"
"System.DirectoryServices.DirectoryServicesCOMException (0x80072020): An operations error occurred"
The Group Policy Modeling report requires Domain Admin access and it is not supported when using a minimum permissions account.
This error can also occur if the Application Directory Partition already exists, it may need to be deleted and recreated manually. If the partition is created manually on a DC, the report wizard should be configured to use that DC to generate the report (unless the partition is configured to be replicated to other DC's). The below steps to create/delete the partition are from the GPOADmin User Guide:
create nc dc=staging,dc=gpoadmin DomainController
For every domain controller which might be used to run the Group policy modeling report on, type the following:
add nc replica “dc=staging,dc=gpoadmin” DomainControllerName
delete nc dc=staging,dc=gpoadmin