[playground-elements] "Hello World" Playground page not rendered in Firefox

[hernanmd]

Description

The Playground page does not render the "Hello World" example using Firefox 100.0 (64-bit) in macOS Big Sur. Reproducible with all addons disabled. Does it work correctly in Safari Version 14.1.2 (16611.3.10.1.6). Other browsers not checked.

Steps to Reproduce

Open (https://lit.dev/playground/)[https://lit.dev/playground/]

2. See this output...

Live Reproduction Link

https://lit-html.stackblitz.io/ stuck with "Starting dev server" and this code:

// Import lit-html functions
import { html, render } from 'lit-html';

// Define a template function
const myTemplate = name =>
  html`
    <h1>Hello ${name}!</h1>
  `;

// Render the template with some data
render(myTemplate('lit-html'), document.body);

Actual Results

Browsers Affected

• Chrome
• Firefox
• Edge
• Safari 11
• Safari 10
• IE 11

[veikkoeeva]

The page https://lit.dev/playground/ renders for me correctly in Firefox 101.0b9 (64-bit, nightly) and 100.0.2 (64-bit).

At the moment the Stackblitz link does not open for me in Edge or Firefox or Chrome. Edge and and Chrome are just stuck failing to load resources. Firefox tells the following (but probably the underlying reason is the same).

Creating a new Stackblitz TS or some other project seem to work fine. Maybe this has something to do with current https://lit-html.stackblitz.io/ playground?

[justinfagnani]

I wasn't able to reproduce the playground issue on Firefox 101. Can you try again and check console logs? It's possible the service worker got stuck on an old version, though we've tried to detect that situation and reload the service worker.

[hernanmd]

Hi Justin.
I checked with up to date FF 101.0.1 (64-bit). I didn't checked yet disabling all plugins but so far the problem still persists, this is the output of about:config with serviceworker parameters (none was modified)

![Screen Shot 2022-06-17 at 01 13 18](https://user-images.githubusercontent.com/4825959/174193160-50cd40da-f79d-4329-b9eb-2afcfd4cc9bb.png

about:serviceworkers output is "No Service Workers Registered"

Console output is empty.

Let me know if I could check something else.

[muratcorlu]

I'm not sure if this is same problem but Playground Result part is not working also in Safari 15.5 in MacOS Monterey 12.4

Apparently, it tries to open this URL: https://playground.lit.dev/__playground_swfs_f56081d9/spot0v/index.html But this URL returns 404 for me.

[AndrewJakubowicz]

@muratcorlu From your images, is it possible that your Grammarly extension is causing the issue? Could you try temporarily disabling it to verify?

Found a possibly related issue, as well as ianstormtaylor/slate#733

[muratcorlu]

@AndrewJakubowicz Disabling all extensions, including Grammarly, didn't fix the issue. But then I tried "Develop -> Empty Caches" menu, and it started working again. After that, I enabled Grammarly again, and there was no issue.

I assume somehow playground service worker was not updated correctly.