Hello ABDOU -ID,
Thank you for posting in Q&A forum.
Do you have another Domain Controller except this Windows server 2012 Domain Controller? If so, can you edit the default domain policy using the same domain account on another domain controller?
If you can edit the default domain policy using the same domain account on another domain controller, it seems there is AD replication problem.
If you cannot edit the default domain policy using the same domain account on another domain controller, or if you have only one 2012 domain controller, maybe it is related to permission.
1.Please check if your account is domain admin account.
2.Please click the default domain policy and check the permission under "Delegation" tab (the permissions below are default permissions).
You can try to change the permission based on the default permissions in test lab environment if needed.
I hope the information above is helpful.
If you have any questions or concerns, please feel free to let us know.
Best Regards,
Daisy Zhou
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