ERR_NGROK_SHIP_CONTAINER_IMAGE_PULL_CREDENTIAL_REQUIRED: Registry HOST requires a credential to read IMAGE - ngrok documentation

What does ERR_NGROK_SHIP_CONTAINER_IMAGE_PULL_CREDENTIAL_REQUIRED mean?

ngrok returns ERR_NGROK_SHIP_CONTAINER_IMAGE_PULL_CREDENTIAL_REQUIRED with this message:

Registry <HOST> requires a credential to read <IMAGE>.

Where can I get more help with ERR_NGROK_SHIP_CONTAINER_IMAGE_PULL_CREDENTIAL_REQUIRED?

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