Playwright fails to run a WebWorker in a Chromium/FireFox "extension".

Issue microsoft/playwright#38638

Context:

I can not test my project with Playwright. This guy is not finishing loading at all.

My current Browser extension/add-on "pre_worker_central_msg_log" branch of

"https://github.com/44xtc44/station-recorder.git".

Browser stuck on loading indexedDB via WebWorker to free the main thread for animations.

Animation is also not shown by the way. Seem the failure blocks all long running former executions.

An empty error object is shown in Dev Tools console.

Hint: Fixed issue WebWorker non-extensions microsoft/playwright#4487

Playwright Version: 1.57.0

Operating System: Linux

Node.js version: 24.12.0; ES modules used

Browser: Chromium

manifest.json Version: 3

System:

Linux: 6.8.0-58-generic

Memory: 32.00 GB

I have created a minimal example to reproduce the issue. You can find it here:

https://github.com/44xtc44/BUG-Playwright-fail-WebWorker-Extension.git

Steps to reproduce

(A) Extension App.

Have a web application extension/add-on with a few web workers that performs any actions.

Configure "postMessage", "onmessage", "onerror".

The WebWorker instance don't receive a message, only an empty error object.

Or see the repo I have created - https://github.com/44xtc44/BUG-Playwright-fail-WebWorker-Extension.git

"npm install" in the package root folder then.

(B) Extension manifest.json Version 3

Since Browser brands use different manifest syntax, copy from /tests/manifest/<brand>.

Playwright FireFox (Nightly) test run shows the same error as Chromium.

To exclude the started Browser instance from failure start

firefox module via test module and keep the browser instance open.

"about:debugging" add temporary Add-on, locate -> bug report repo root folder manifest.json. Fire.

Browser instance works fine, WebWorker instance responds accordingly.

(C) Test "single" browser extension. manifest.json must be adapted. See (C)

import { chromium } from "playwright"; or import { chromium } from "playwright/test";

or also tested:

import { firefox } from "playwright"; or import { firefox } from "playwright/test";

run in terminial /tests/end2end/

> npx run-func chromium.js homePageOpen -y

Expected behavior

I would expect to see a web worker message.

Actual behavior

I can not see web worker message. Only an empty error object.

Additional context

none

Environment

Linux, Browser Tests