Group Policy Object cannot be opened or edited with the error: Failed to open Group Policy Object. You might not have the appropriate rights.

Details: The volume for a file has been externally altered so that the opened file is no longer valid.


Solution:

• Get GPO GUID: from Group Policy Management Console (GPMC) –> choose GPO –> from right pane go to Details tab –> go to Unique ID field.
• Open the path: C:\Windows\SYSVOL\sysvol\<Domain>\Policies\<GPO GUID>\User
• Delete “registry.pol” file.

Note: if you have migrated SYSVOL replication type from FRS to DFSR, open the path:  C:\Windows\SYSVOL_DFSR\sysvol\<Domain>\Policies\<GPO GUID>\User