> ## 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 811

## ERR\_NGROK\_811

Could not negotiate a protocol version. Requested: "`REQUESTED`", Supported: `SUPPORTED`"

## 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_811)