使用stomp.js与sprinboot的WebSocket集成，Failed to deliver message(s)

Question

前段代码如下：

function connect() {
    try {
        if ("WebSocket" in window) {
            var socket = new SockJS(path + "/examSocket");
            stompClient = Stomp.over(socket);
            stompClient.connect({cyryzj: cyryzj, ksid: ksid}, function (frame) {
                console.log('连接成功: ' + frame);
                stompClient.subscribe('/exam/subscribe/' + cyryzj, function (frame) {
                    console.log('订阅成功: ' + frame);
                }/*, {'cyryzj': cyryzj}*/);
            }, function errorCallBack(error) {
                console.log('连接失败【' + error + '】');
                reconnect();
            });
        } else {
            alert("您的浏览器不支持Websocket通信协议，请使用Chrome或者Firefox浏览器！");
            return;
        }
    } catch (e) {
        console.log('connect exception', e)
        reconnect();
    }
}

function send(ksid) {
    let time = $(".time").text();
    //console.log('crontabRefreshTTL:time', time)
    stompClient.send("/crontabRefreshExamTime/" + ksid + "/" + cyryzj + "/" + time, {});
}

java代码如下：

  @MessageMapping("/crontabRefreshExamTime/{ksid}/{cyryzj}/{time}")  // 获取客户端的推送信息
    public String crontabRefreshExamTime(@DestinationVariable("cyryzj") final String glzj,
                                         @DestinationVariable("ksid") final String ksid,
                                         @DestinationVariable("time") final String time) {
        //log.info("从业人员主键：" + cyryzj + " 考试ID：" + ksid);
        ExamKsxx examKsxx = (ExamKsxx) redisUtils.hget("ksxx", ksid);
        if (Objects.isNull(examKsxx)) {
            examKsxx = examKsxxService.getOne(new QueryWrapper<ExamKsxx>().lambda().eq(ExamKsxx::getLsh, ksid).eq(ExamKsxx::getSfyx, OLD_DEL_FLAG));
            if (Objects.nonNull(examKsxx)) {
                // 根据考卷时长决定当前考试信息在redis的逾期时长
                long expireTimeLong = examKsxx.getKsjssj().getTime() - examKsxx.getKskssj().getTime();
                long expireTimeSeconds = TimeUnit.MILLISECONDS.toSeconds(expireTimeLong);
                redisUtils.hset("ksxx", examKsxx.getLsh(), examKsxx, expireTimeSeconds);
            }
        }
        String kslsh = examKsxx.getLsh();
        String item = kslsh + ":" + glzj;
        // 将考试时间更新
        Date date = (Date) redisUtils.hget(CURR_EXAM_EXPIRE_TIME, item);
        if (Objects.nonNull(date)) {
            String formatDate = DateUtil.format(date, DateUtil.PATTERN_DATE);
            String clientTime = Func.toStr(time);
            String refreshExpire = formatDate + " " + clientTime;
            Date time2 = tools.util.DateUtil.parse(refreshExpire, PATTERN_DATETIME);
            redisUtils.hset(CURR_EXAM_EXPIRE_TIME, item, time2);
        }

        return null;
    }

错误如下：

ERROR: Servlet.service() for servlet [dispatcherServlet] in context with path [/sysgl] threw exception [Request processing failed; nested exception is org.springframework.web.socket.sockjs.

SockJsException: Uncaught failure in SockJS request, uri=http://xxxxx/sysgl/examSocket/464/thlqjmnl/xhr_send?t=1633698025096; 

nested exception is org.springframework.web.socket.sockjs.SockJsMessageDeliveryException: Failed to deliver message(s) [SEND
destination:/crontabRefreshExamTime/d7e2e214e190462e8b905fe4517d4b2f/d27cffe3e28e463984a789478b712529/00:56:45

 ] for session thlqjmnl; nested exception is org.springframework.web.socket.sockjs.SockJsMessageDeliveryException: Failed to deliver message(s) [SEND
destination:/crontabRefreshExamTime/d7e2e214e190462e8b905fe4517d4b2f/d27cffe3e28e463984a789478b712529/00:56:45

 ] for session thlqjmnl: Session closed] with root cause
org.springframework.web.socket.sockjs.SockJsMessageDeliveryException: Failed to deliver message(s) [SEND
destination:/crontabRefreshExamTime/d7e2e214e190462e8b905fe4517d4b2f/d27cffe3e28e463984a789478b712529/00:56:45

 ] for session thlqjmnl: Session closed

我在前端会setInterval调用send()方法，去做操作，每5s执行一次.