Issues with Auth or Credentials

Hi everyone, I’m having trouble with the cTrader Open API (using the ctrader-open-api Python library, version 0.9.3) and would really appreciate some help.

I’m trying to connect to the demo endpoint (demo.ctraderapi.com:5035) and authenticate my application using ProtoOAApplicationAuthReq (payloadType 2101). The connection is established successfully, and I can send the authentication request with my clientId and clientSecret. However, the server responds with ProtoOAVersionRes (payloadType 51) repeatedly, and then the connection is lost with the error: Connection to the other side was lost in a non-clean fashion: Connection lost.

Here are the key details of the issue:

The ProtoOAVersionRes message is empty (no fields are populated), which suggests that the library is not deserializing the message correctly.

The server never sends ProtoOAApplicationAuthRes (payloadType 2102) or ProtoOAErrorRes (payloadType 1), so the authentication process doesn’t proceed.

I’ve tried updating the Protobuf files by downloading the latest .proto files from the Spotware OpenAPI GitHub repository and regenerating them with protoc, but the issue persists.

I’m using protobuf==3.20.1 and Twisted==24.3.0, as required by ctrader-open-api==0.9.3.

I’ve also disabled certificate verification to rule out SSL/TLS issues, but the problem remains.

Here’s a summary of the output I’m getting:

Connection is established.

Authentication request is sent (payloadType 2101).

Server responds with ProtoOAVersionRes (payloadType 51) a few times.

Connection is lost with the error mentioned above.

I suspect the issue might be related to one of the following:

Invalid or expired clientId/clientSecret (though I’ve used these credentials successfully in the past).

A protocol version mismatch between the library and the server (I don’t know the server’s supported protocol version).

A bug in the ctrader-open-api==0.9.3 library, especially with Protobuf deserialization.

Could anyone help me with the following?

How can I confirm if my clientId and clientSecret are still valid?

What is the current protocol version supported by the demo server (demo.ctraderapi.com:5035)?

Is there a known issue with ctrader-open-api==0.9.3 and Protobuf deserialization? Should I use a different library or approach?

Am I missing a step in the authentication flow? For example, do I need to send a specific message after receiving ProtoOAVersionRes?

Any insights or suggestions would be greatly appreciated! Thank you in advance for your help.