ERR_NGROK_423: The reserved domain name is limited to MAX characters; you are using VAL characters - ngrok documentation

What does ERR_NGROK_423 mean?

ngrok returns ERR_NGROK_423 with this message:

The reserved domain name is limited to <MAX> characters; you are using <VAL> characters.
The name you've requested is: <DOMAIN>

Troubleshoot ERR_NGROK_423 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_423?

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