ERR_NGROK_1117: Cannot request a random port with a custom bind address ADDR in '-R ADDR:0:' - ngrok documentation

What does ERR_NGROK_1117 mean?

ngrok returns ERR_NGROK_1117 with this message:

Cannot request a random port with a custom bind address <ADDR> in '-R <ADDR>:0:'.
You may either specify a reserved TCP address with '-R address:port:' or you may let the server choose a random remote port for you with '-R 0:'.

Example: ssh -R 0:localhost:22 ...
Example: ssh -R 1.tcp.eu.ngrok.io:21412:localhost:22 ...

Troubleshoot ERR_NGROK_1117 with your AI agent. Connect it to the ngrok MCP server, then ask what caused the error and how to fix it.

Where can I get more help with ERR_NGROK_1117?

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