ERR_NGROK_3121: The nonce cookie required to finish authorization with PROVIDER is missing - ngrok documentation

What does ERR_NGROK_3121 mean?

ngrok returns ERR_NGROK_3121 with this message:

The nonce cookie required to finish authorization with <PROVIDER> is missing.

Start over to try again.

Troubleshoot ERR_NGROK_3121 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_3121?

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