I will need some more information on the issue because I am not able to recreate it at my end (it works fine).
You have changed your permissions on your patent page to " Administrators only" and inherited it to all child pages and it worked, then you try to change permissions to the parent page again and you get this error.
Please tell me which version of Sitefinity you are using and is the project upgraded ( if it is from which version).
Looking forward to your reply.
the Telerik team
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