anchor.diff:      lager:info("Stopping monitoring via web on ~w:~w/~w~n",[M,F,A]),
   
       xprof_tracer:demonitor(MFA),
  -    {ok, ResReq} = cowboy_req:reply(204, Req),
  +    {ok, ResReq} = cowboy_req:reply(204, ?HDR_NO_CONTENT, Req),
       {ok, ResReq, State};
   
   handle_req(<<"mon_get_all">>, Req, State) ->
  
positive.code:     {ok, ResReq} =
          case xprof_tracer:monitor(Query) of
              ok ->
                  cowboy_req:reply(204, Req);
              {error, already_traced} ->
                  cowboy_req:reply(204, Req);
              _Error ->
                  cowboy_req:reply(400, Req)
          end,
  
negative.code:     {ok, ResReq} =
          case xprof_tracer_handler:capture_stop(MFA) of
              ok ->
                  cowboy_req:reply(204, ?HDR_NO_CONTENT, Req);
              {error, not_found} ->
                  cowboy_req:reply(404, Req)
          end,
  