beast: How to receive data while http post without "bad chunk"?

While porting a client from curl to beast (v57 and v58) i am not able to receive data in rpc (http post).

class client_impl : public virtual client_base
{
public:
    client_impl(const std::string& host, const std::string& port)
    :
        _host(host),
        _service(),
        _socket(_service)
    {
        std::clog << BEAST_VERSION_STRING << std::endl;
        boost::asio::ip::tcp::resolver resolver{_service};
        boost::asio::ip::tcp::resolver::query query{host, port};
        boost::asio::connect(_socket, resolver.resolve(query));
    }

    virtual value_t call(const string_t& service, const string_t& method, const list_t& arguments) override
    {
        // Send HTTP request using beast
        beast::http::request<beast::http::string_body> request;
        request.method(beast::http::verb::post);
        request.target(service);
        request.insert(beast::http::field::host, _host);
        request.insert(beast::http::field::user_agent, "libhessian/1.0");
        request.insert(beast::http::field::accept, "*/*");
        request.insert(beast::http::field::content_type, "x-application/hessian");
        request.body = generate(method, arguments);
        request.prepare();
        std::clog << request << std::endl;
        beast::http::write(_socket, request);

        // Receive and print HTTP response using beast
        beast::flat_buffer buffer;
        beast::http::response<beast::http::string_body> response;
        beast::http::read(_socket, buffer, response); // ERROR HERE
        std::clog << response << std::endl;

        const content_t content = parse(response.body);
        return boost::apply_visitor(content_visitor(), content);
    }

    virtual bool negotiate(const string_t& resource) override
    {
        throw std::runtime_error("beast http does not support spnego.");
    }

private:
    std::string _host;
    boost::asio::io_service _service;
    boost::asio::ip::tcp::socket _socket;
};

The request seems to be ok (same as in curl):

POST /test/test2 HTTP/1.1
Host: hessian.caucho.com
User-Agent: libhessian/1.0
Accept: */*
Content-Type: x-application/hessian
Content-Length: 15

HC	replyTrue�

But while reading the response i always get “bad chunk” error.

Verbose info from same call using curl:

*   Trying 54.235.109.78...
* TCP_NODELAY set
* Connected to hessian.caucho.com (54.235.109.78) port 80 (#0)
> POST /test/test2 HTTP/1.1
Host: hessian.caucho.com
User-Agent: libhessian/1.0
Accept: */*
Content-Type: x-application/hessian
Content-Length: 15

* upload completely sent off: 15 out of 15 bytes
< HTTP/1.1 200 OK
< Server: Resin/4.0.s150303
< Content-Type: x-application/hessian
< Transfer-Encoding: chunked
< Date: Thu, 15 Jun 2017 14:59:50 GMT
< 
* Curl_http_done: called premature == 0
* Connection #0 to host hessian.caucho.com left intact

So i missed something in the impl?!

Best regard, Mike…