ERR_NGROK_6023: HTML content may only be served in this region after you upgrade to a paid account - ngrok documentation

What does ERR_NGROK_6023 mean?

ngrok returns ERR_NGROK_6023 with this message:

HTML content may only be served in this region after you upgrade to a paid account.

Where can I get more help with ERR_NGROK_6023?

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