Subscriptions request with response 400 / error validating json (Gamemaker Studio 2)

[warzonefury]

Hello !

I’m coding a Twitch library on Gamemaker Studio 2 to listen to events from a channel. So far so good, it works flawlessly through subscription servers and Twitch websocket. On the other hand, with the test server by CLI, in response to my subscription requests I take a:

{"response_headers":10.0,"http_status":400.0,"url":"http:\/\/127.0.0.1:8080\/eventsub\/subscriptions","id":9.0,"status":0.0,"result":"{\"error\":\"Bad Request\",\"message\":\"error validating json\",\"status\":400}"}

I checked my code several times, the JSON is good. Maybe a problem in headers? I’ll give you my GML code if it helps:

function __twitch_sub_to_events(){								
	__twitch_message("Subscribe to all events...");
	
	global.twitch_state = TWITCH_STATE.SUBSCRIPTION_EVENT_PENDING;
	
	var _events = twitch_get_sub_event();
	var _nb_event_to_sub = array_length(global.twitch_user_sub_events);
	var _url = global.debug_test ? global.twitch_url_subscribtions_debug : global.twitch_url_subscribtions;
	
	for (var _i = 0; _i < _nb_event_to_sub; _i++) {		
		var _event = _events[$ global.twitch_user_sub_events[_i]];
		
		var _headers = ds_map_create();
		ds_map_add(_headers, "Authorization", __capitalize(global.twitch_token_type) + " " + string(global.twitch_access_token));
		ds_map_add(_headers, "Client-Id", string(global.twitch_client_id));
		ds_map_add(_headers, "Content-Type", "application/json");
		
		var _body = {
			"type": _event[$ "type"],
			"version": _event[$ "version"],
			"condition": _event[$ "condition"],
			"transport": {
				"method": "websocket",
				"session_id": string(global.twitch_session_id)
			}
		};
		
		http_request(_url, "POST", _headers, json_stringify(_body));
		__twitch_message("Subscribe request to ", _event[$ "type"], " sent");		
	};
}

Thank you very much for your help !