ERR_HTTP2_PROTOCOL_ERROR error on AJAX request

Hi Sergio,
A client tries to make an AJAX request via Axios to my REST server, which is based on TsgcWSHTTP2WebBrokerBridgeServer.
It always returns ERR_HTTP2_PROTOCOL_ERROR.
I'm attaching a screenshot of the code they're using (using the Axios JavaScript library).

What could this be due to?