[Question] How to update firefox default prefs

[star-kashyap]

@arjun27 Can you please help unblocking us regarding below issue.
We are testing a streaming application and not able to play some contents (DRM) on firefox because media.gmp-manager.updateEnabled is set false in playwright.cfg file.

// Disable download and usage of OpenH264: and Widevine plugins
pref("media.gmp-manager.updateEnabled", false);

Is there a way to turn this pref true via api ?

[mxschmitt]

As a workaround maybe you could use a custom user directory like shown here. There you can have a file with your user preferences: #917 (comment)

---

Maybe this can be standardised for all the browsers and added natively to the Playwright API, since:

• Firefox has user preferences: about:config
• Chromium has flags: chrome://flags
• WebKit has experimental features not fully identical but goes into the direction

[pavelfeldman]

You can use firefoxUserPrefs

[illright]

For anyone coming to this thread in the future looking to change Firefox user preferences in the playwright.config.ts:

// playwright.config.ts
const config = defineConfig({
  projects: [
    {
      name: "firefox",
      use: {
        ...devices["Desktop Firefox"],

        launchOptions: {
          firefoxUserPrefs: { "dom.webgpu.enabled": true },
        },
      },
    },
  ]
});