ERR_NGROK_9020: Your legacy account is not authorized to use the websocket to TCP converter - ngrok documentation

What does ERR_NGROK_9020 mean?

ngrok returns ERR_NGROK_9020 with this message:

Your legacy account is not authorized to use the websocket to TCP converter.

Upgrade to a new paid plan at: https://dashboard.ngrok.com/billing/choose-a-plan

Where can I get more help with ERR_NGROK_9020?

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