ERR_NGROK_SHIP_DOMAIN_MANAGED_CERT_REQUIRED: This domain does not use a managed certificate - ngrok documentation

What does ERR_NGROK_SHIP_DOMAIN_MANAGED_CERT_REQUIRED mean?

ngrok returns ERR_NGROK_SHIP_DOMAIN_MANAGED_CERT_REQUIRED with this message:

This domain does not use a managed certificate.

Where can I get more help with ERR_NGROK_SHIP_DOMAIN_MANAGED_CERT_REQUIRED?

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