> ## Documentation Index
> Fetch the complete documentation index at: https://ngrok.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Error 600

## ERR\_NGROK\_600

Invalid ACL rule. An ACL rule must be '\*' or start with 'bind:'. The bind value must match the format of a domain, address, or label. You specified: `RULE`.

## Further help

If you're having trouble resolving this error, please reach out to [support@ngrok.com](mailto:support@ngrok.com?subject=Help%20with%20ERR_NGROK_600)