Getting error CERT_PKIXVerifyCert for dl.google.com failed err=-8181 when run a embedded html

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Hi,
I am getting this CERT_PKIXVerifyCert for dl.google.com failed err=-8181 error when I run a video through embedded html option as a result of which my Ubuntu Xibo Client sreen remians blank.
I tested the html on every browser of my Ubuntu OS(default ubuntu browser,chromium browser and firefox),it is working fine there.
But it is not working but when run xibo client. Can you tell me how Xibo call any webservice.

My html code is

<script src="https://code.jquery.com/jquery-3.2.1.min.js"></script>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.18.1/moment.min.js"></script>
<script>
    function startTime() {

        var openWeatherMapAppID = "4e5259477189f22a37f74c6ada4db42e";
        var country = "Singapore";
        var unit = "metric"
        var openWeatherMapUrl = "http://api.openweathermap.org/data/2.5/weather?q=" + country + "&units=" + unit + "&appid=" + openWeatherMapAppID;

        //var xmlHttp = new XMLHttpRequest();
        //xmlHttp.open("GET", openWeatherMapAppID, false); // true for asynchronous 
        //xmlHttp.send();
        //xmlHttp.onreadystatechange = function () {
        //    if (xmlHttp.readyState == 4 && xmlHttp.status == 200) {
        //        alert(xmlHttp.responseText);
        //    }
        //}

        $.get(openWeatherMapUrl, function (data) {
            var temperature = data.main.temp + "°C";
            var iconUrl = "http://openweathermap.org/img/w/" + data.weather[0].icon + ".png";
            var weatherText = data.weather[0].description;

            $("#lblTemperature").text(temperature);
            $("#imgWeatherIcon").attr("src", iconUrl);
            $("#lblWeatherText").text(weatherText);
        });

        var today = new Date();
        var h = today.getHours();
        var m = today.getMinutes();
        var s = today.getSeconds();
        var month = today.getUTCMonth() + 1; //months from 1-12
        var day = today.getUTCDate();
        var year = today.getUTCFullYear();
        m = checkTime(m);
        s = checkTime(s);
        document.getElementById('lblTime').innerHTML = h + ":" + m + ":" + s;
        document.getElementById('lblDate').innerHTML = day + "/" + month + "/" + year;

        var t = setTimeout(startTime, 1000);
    }
    function checkTime(i) {
        if (i < 10) { i = "0" + i };  // add zero in front of numbers < 10
        return i;
    }
</script>

Thanks in advance