Error code: 40017 - Unsupported protocol version or Invalid API version specified

Stateless connections must specify a protocol version 

This error will be seen when not specifying or using an invalid protocol version in the request parameters of a server-sent events request. Currently the supported versions are 1.1 or greater (e.g. 1.2, 2.0)

See our Server-sent events documentation and API reference for more information on mandatory parameters

Invalid api version specified

This error will be seen when using an invalid protocol version in the request parameters of a websocket connection to Ably. Valid versions are 0.8, 0.9, 1.1, 1.2 and 2.0