ERR_NGROK_SHIP_APP_ENVIRONMENT_TRACKING_REF_REQUIRED: Environment NAME must have a 'tracking_ref' - ngrok documentation

What does ERR_NGROK_SHIP_APP_ENVIRONMENT_TRACKING_REF_REQUIRED mean?

ngrok returns ERR_NGROK_SHIP_APP_ENVIRONMENT_TRACKING_REF_REQUIRED with this message:

Environment <NAME> must have a 'tracking_ref'.

Where can I get more help with ERR_NGROK_SHIP_APP_ENVIRONMENT_TRACKING_REF_REQUIRED?

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