ERR_NGROK_203: The API authentication you specified is properly formed, but it is invalid - ngrok documentation

What does ERR_NGROK_203 mean?

ngrok returns ERR_NGROK_203 with this message:

The API authentication you specified is properly formed, but it is invalid. API keys and instructions are available on your dashboard: https://dashboard.ngrok.com/api-keys

Troubleshoot ERR_NGROK_203 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_203?

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