Service Worker Fails on caches.open() - progressive-web-apps

Question

I'm trying to get a basic service worker up and running.
The problem I have is that when I run "caches.open()", the browser throws a
sw.js:1 Uncaught (in promise) DOMException: Unexpected internal error
Commenting out the caches.open removes the exception.
How can I get more information from the browser to tell me what's wrong?
Here's the service worker and registration code.
var CACHE_NAME = 'pwacache-v1';
var urlsToCache = [
'/',
'main.css'
];
self.addEventListener('install', function (event) {
// Perform install steps
console.log('install');
try {
event.waitUntil(getFiles());
} catch (ex) {
console.log(ex);
}
});
function getFiles() {
console.log('opening: ' + CACHE_NAME );
/*
triggers Uncaught (in promise) DOMException: Unexpected internal error
*/
caches.open(CACHE_NAME).then(function (cache) {
return Promise.all(
urlsToCache.map(function (url) {
console.log(url);
return cache.add(url).catch(function (reason) {
console.log([url + "failed: " + String(reason)]);
});
}) // end of map
);
});
console.log('waiting 3...')
}
And the registration code
// https://developers.google.com/web/fundamentals/primers/service-workers/registration
if ('serviceWorker' in navigator) {
window.addEventListener('load', function() {
navigator.serviceWorker.register('sw.js');
});
}
I do see the sw.js registered in Chrome's 'Application' tab.

Answer 1

You need to return a promise from getFiles() in order for the event.waitUntil() to actually wait for the async work. So I recommend returning the promise returned by your promise chain started with caches.open().
Without this its possible the service worker is being terminated before the async work can complete.