ERR_NGROK_2231: Invalid configuration for ACTION: CONFIG contains duplicate values: DUPLICATES - ngrok documentation

What does ERR_NGROK_2231 mean?

ngrok returns ERR_NGROK_2231 with this message:

Invalid configuration for <ACTION>: <CONFIG> contains duplicate values: <DUPLICATES>.

Where can I get more help with ERR_NGROK_2231?

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