I'm having a strange problem creating or editing Group Policies on a standalone Windows 2016 server configured as DC for a single domain. The AD is orginating from a Windows 2012 Essentials server, the current 2016 server have been configured as a DC for the same domain and all FSMO roles have been transferred and finally the old Windows 2012 Essentials server have been decomissioned and recycled.
However, this 2016 server have developed this strange problem when creating or editing Group Policies, access is denied. I have checked DCDIAG, no problems. I have configured an extra DC, just to check if it was possible to edit GPO's on a another server, but it was the same problem. This extra DC have been removed afterwards. It seems to me that the problem might be the ability to write to the directories or files containing the GPO's. I have done intensive research, but I have not found anything helpful.
When creating a new Group Policy, I get an error "Access is denied". No events are logged. When editing an existing Group Policy, I get an error: "Error (0x80070005) occured saving settings file. Access is denied." No events are logged.
The server is configured as a Domain Controller, Active Directory Certificate Authority server and Remote Access server.