ERR_NGROK_5303: The endpoint configuration "ECID" is not attached to any domains

What does ERR_NGROK_5303 mean?

ngrok returns ERR_NGROK_5303 with this message:

The endpoint configuration "<ECID>" is not attached to any domains.

Troubleshoot ERR_NGROK_5303 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.