Hi, No, this option was not set. If I set it explicitly to "no", the behavior stays the same. However, if I set it to "yes", then the error message disappears. From the documentation, I would have expected it exactly the other way round. However, xhttp module README says, that you have to set it to yes to prevent errors. So thanks for the hint. Regards, Sebastian ________________________________ From: Daniel-Constantin Mierla &lt;miconda(a)gmail.com&gt; Sent: Wednesday, September 11, 2024 19:10 To: Kamailio (SER) - Users Mailing List &lt;sr-users(a)lists.kamailio.org&gt; Cc: Sebastian Damm &lt;sdamm(a)pascom.net&gt; Subject: Re: [SR-Users] SIP parse error for self-generated Websocket reply Hello, On 11.09.24 18:02, Sebastian Damm via sr-users wrote: Hello, We try to introduce a small websocket sidecar to our Kamailio servers, which runs on the same host. It connects to the regular TCP socket of our Kamailios, and in the XHTTP request route, we do just this: if path == "/sidecar": KSR.websocket.handle_handshake() return 1 On every new connect, Kamailio logs a parse error for the reply it generates. Sep 11 15:42:35 sipproxy /usr/sbin/kamailio[552]: ERROR: <core> [core/parser/parse_fline.c:272]: parse_first_line(): parse_first_line: bad message (offset: 22) Sep 11 15:42:35 sipproxy /usr/sbin/kamailio[552]: ERROR: <core> [core/parser/msg_parser.c:790]: parse_msg(): ERROR: parse_msg: message=<HTTP/1.1 101 Switching Protocols Sia: SIP/2.0/TCP 100.74.11.1:46422 Sec-WebSocket-Protocol: sip Upgrade: websocket Connection: upgrade Sec-WebSocket-Accept: 60dPbzcRW6up7z92kDlxkqL2WlY= Content-Length: 0 Sep 11 15:42:35 sipproxy /usr/sbin/kamailio[552]: ERROR: <core> [core/msg_translator.c:3402]: build_sip_msg_from_buf(): parsing failed I saw this error in other questions from a while ago, but without a solution. What could be the reason for this? is this parameter set? - https://www.kamailio.org/wikidocs/cookbooks/5.8.x/core/#http_reply_parse Cheers, Daniel -- Daniel-Constantin Mierla (@ asipto.com) twitter.com/miconda -- linkedin.com/in/miconda Kamailio Consultancy, Training and Development Services -- asipto.com Kamailio Advanced Training, October 8-10, 2024 -- asipto.com