What does "Reconstructed hostname is not the same as the posted hostname" mean?

I have used this method to update with my credentials:
curl --data-urlencode hostname=tyrion.hn.org \
     --data-urlencode password=OpenSesame \
     --data-urlencode ipv4=192.168.1.10 \
     https://tyrionzqj32v3.hn.org/update.php
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