ERR_NGROK_SHIP_REGISTRY_HOST_INVALID: The 'host' value HOST is not a registry host: REASON - ngrok documentation

What does ERR_NGROK_SHIP_REGISTRY_HOST_INVALID mean?

ngrok returns ERR_NGROK_SHIP_REGISTRY_HOST_INVALID with this message:

The 'host' value <HOST> is not a registry host: <REASON>

Where can I get more help with ERR_NGROK_SHIP_REGISTRY_HOST_INVALID?

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