When trying to configure a namerserver as part of the Secondary DNS offering from Cloudflare (nsXXXX.secondary.cloudflare.com), an error is thrown.
Upon contacting the Registrar, their services confirm that the nameservers from Cloudflare cannot be added at this time.
Error depends on the system, and might be:
Entity reference not found Authorization error; Unable to create foreign nameserver
This issue may arise when one of our nameservers used for secondary nameservers are removed from the Verisign side.
The Cloudflare Engineering team needs to be engaged through Support to make sure the nameserver gets registered again manually with Verisign.