ERR_NGROK_SHIP_PUBLISH_TARGET_DOCKER_HUB_UNAVAILABLE: Docker Hub did not answer while ngrok prepared repository REPOSITORY: REASON - ngrok documentation

What does ERR_NGROK_SHIP_PUBLISH_TARGET_DOCKER_HUB_UNAVAILABLE mean?

ngrok returns ERR_NGROK_SHIP_PUBLISH_TARGET_DOCKER_HUB_UNAVAILABLE with this message:

Docker Hub did not answer while ngrok prepared repository <REPOSITORY>: <REASON>

Where can I get more help with ERR_NGROK_SHIP_PUBLISH_TARGET_DOCKER_HUB_UNAVAILABLE?

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