ERR_NGROK_381: The host HOST and port PORT you requested is already reserved by an edge - ngrok documentation

What does ERR_NGROK_381 mean?

ngrok returns ERR_NGROK_381 with this message:

The host <HOST> and port <PORT> you requested is already reserved by an edge.

Where can I get more help with ERR_NGROK_381?

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