Chrome Push Notification: This site has been updated in the background

Short Answer: You should use event.waitUntil and pass a promise to it, which returns showNotification eventually. (if you have any other nested promises, you should also return them.)

I was expriencing the same issue but after a long research I got to know that this is because delay happen between PUSH event and self.registration.showNotification(). I only missed return keyword before self.registration.showNotification()`

So you need to implement following code structure to get notification:

var APILINK = "";
 self.addEventListener('push', function(event) {
          fetch(APILINK).then(function(response) {
        return response.json().then(function(data) {
                  var title = data.title;
                  var body = data.message;
                  var icon = data.image;
                  var tag = 'temp-tag';
                  var urlOpen = data.URL;

                return  self.registration.showNotification(title, {
                      body: body,
                      icon: icon,
                      tag: tag

Minimal senario:

self.addEventListener('push', event => {
  const data =;
    // in here we pass showNotification, but if you pass a promise, like fetch,
    // then you should return showNotification inside of it. like above example.
    self.registration.showNotification(data.title, {
      body: data.content

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