ERR_NGROK_SHIP_DOMAIN_NAME_HOST_REQUIRED: Domain name has no hostname - ngrok documentation

What does ERR_NGROK_SHIP_DOMAIN_NAME_HOST_REQUIRED mean?

ngrok returns ERR_NGROK_SHIP_DOMAIN_NAME_HOST_REQUIRED with this message:

Domain name has no hostname. ngrok reads only the host part of a pasted URL.

Where can I get more help with ERR_NGROK_SHIP_DOMAIN_NAME_HOST_REQUIRED?

Email support@ngrok.com and include the error code.