ERR_NGROK_1123: Tunnel '-proxy-proto=PROXYPROTO specifies invalid protocol version

What does ERR_NGROK_1123 mean?

ngrok returns ERR_NGROK_1123 with this message:

Tunnel '-proxy-proto=<PROXYPROTO> specifies invalid protocol version.
Use one of version '1' or '2' to enable proxy proto.

Troubleshoot ERR_NGROK_1123 with your AI agent. Connect it to the ngrok MCP server, then ask what caused the error and how to fix it.

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