ERR_NGROK_SHIP_DOCKERFILE_NOT_FOUND: Dockerfile PATH is missing or empty on branch BRANCH - ngrok documentation

What does ERR_NGROK_SHIP_DOCKERFILE_NOT_FOUND mean?

ngrok returns ERR_NGROK_SHIP_DOCKERFILE_NOT_FOUND with this message:

Dockerfile <PATH> is missing or empty on branch <BRANCH>.

Where can I get more help with ERR_NGROK_SHIP_DOCKERFILE_NOT_FOUND?

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