/explain: Is it supposed to be like this?

Please tell me what am I doing wrong?

Here is my request:

{ "abs_path": "/A/B/Filename-2.exe" }

Here is the response:

HTTP/1.1 400 Bad Request Date: Mon, 16 Nov 2020 21:43:23 GMT Connection: close Content-Length: 350 Content-Type: text/html; charset=UTF-8

400 Bad Request

Bad Request

Unknown message: not_irrelevant('/A/B/Filename-2.exe')

SWI-Prolog httpd at transmatter-laptop