ERR_NGROK_SHIP_PUBLISH_TARGET_DOCKER_HUB_LOGIN_REFUSED: Docker Hub rejected the push credential of publish target ID (HTTP STATUS) - ngrok documentation

What does ERR_NGROK_SHIP_PUBLISH_TARGET_DOCKER_HUB_LOGIN_REFUSED mean?

ngrok returns ERR_NGROK_SHIP_PUBLISH_TARGET_DOCKER_HUB_LOGIN_REFUSED with this message:

Docker Hub rejected the push credential of publish target <ID> (HTTP <STATUS>).

Where can I get more help with ERR_NGROK_SHIP_PUBLISH_TARGET_DOCKER_HUB_LOGIN_REFUSED?

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